beads are about 0·5 mm in diameter. Wind will tangle up the vertical lines. It has already been pointed out that the larva has anal scolophore tactile organs, with external short setae (Pl. 26, Fig. 8). The question arises as to what is the relation between the horizontal runway upon which the larva normally rests, and the vertical lines, some connection presumably being necessary if the larva is to sense the struggles of captured insects. If the larval snare is destroyed, or a larva is put on a suitable rock, it first constructs the horizontal runway, the vertical lines being lowered afterwards. This account only applies to the snare made by larger glow-worms. The very young larvae show a bright light, which alone helps the observer to see their location, but there are no vertical lines, only a runway, and on banks, always a hiding place as well. Presumably newly hatched larvae are able to luminesce and to produce some sort of tiny sticky platform.

In Arapuni, many small larvae rested on steep banks, where the hanging of vertical lines would be quite impossible. These larvae must depend for food on the mucus smears on or along their runways, and when more mature, would have to move to a more favourable place to hang a curtain of fishing lines. It is remarkable that such small larvae can produce a light apparently as bright as that of larvae which are larger, because only by examining the site of the light can one discover whether the owner is large or small. The presence of a light, together with a small sticky area, in the case of small larvae, appears to provide further evidence that the light is designed to attract prey, and is not merely for the dissipation of unwanted energy, as has been suggested.

In one case an isolated larva and snare were seen partly under a rotten log. The aperture leading to its snare was gently widened by cutting with a knife, so that the larva could be used for experiments under natural conditions. On returning in two days to begin the experiments, it was found that the dissatisfied larva had cleared its old site of threads, and had constructed a new snare deeper in. This time the hole was widened so thoroughly that the larva could not get out of reach. On returning again in three days, the larva was found outside the area of the

previously widened hole. It had moved nearly 18 inches away from its original site.

Considerable light can be shed on the relationships of the snare and glow-worm by putting some larvae into a deep glass dish, as in Text-fig. 2. To make a nest the larva uses the angle between the glass lid (L) and the side of the dish (D). Provided the lid of the dish does not haze over with water vapour, it is possible to examine the snare with a binocular microscope.

The snare drawn in Text-fig. 1 was constructed in less than four hours, when the glass dish with larvae was put in a darkroom at midday and examined about 4.30 p.m. The larva was known to have spent about one hour examining the confines of the dish before it chose a place. In Text-fig. 2, the snare is shown in cross section, the black dot in the middle representing the section of the larva. The main runway in which it lies is mainly horizontal as in Text-fig. 1, which is drawn from the side by looking through the side of the dish. The larva lies with its ventral surface upwards, but it does move about so that the front of its body twists in any direction. Examination by the binocular microscope showed that Albert Norris was correct when he stated that the larva lived in a tube. From the left of (LO) to (HO) in Text-fig. 1, the larva is seen to occupy the centre of a glassy mucus runway, which at such places as at (P) seems to be hollow. As the larva moves backwards or forwards it does not push this glassy mucus in front of it, but just stretches it. The anal palps at (LO) where the light organ is situated, lie expanded within transparent mucus in which movements of the palps can take place. If it wishes, the larva can poke its head out of the tube anywhere, the contour of the latter being restored when the larva passes back into it.

The exact relation of the silk lines to the mucus is not understood, but outside the runway, some of the stretchers have mucus droplets held in their angles as at (A). Here the silk and the mucus appear clearly separate, but there seems to be some evidence that the animal is able simultaneously to secrete mucus and silk mixed. The stretchers holding the runway are undoubtedly silk, but where they touch the runway, they pull the mucus out into a cone. The vertical lines (V) were usually not immediately attached to the runway, but were fixed a little off it by side lines (S). The larva which made the snare in Text-fig. 1 was removed that evening to an inverted beaker or a tray on which two rotten branches were set up. During that night it constructed most of another snare (Text-fig. 3) in the only favourable place where vertical lines could be made. Another smaller larva put on the branches at the same time had no place, and stayed in the moss near the ground. It disappeared, probably eaten.

The manner in which the droplets appeared on the silk vertical lines could not at first be observed. They may at first be a continuous outer layer which, by some form of surface tension, resolves into droplets, or they may be secreted one by one. On apriori grounds the former possibility would seem the more likely, but recent observation shows that the latter is correct. Not all the beads were spherical, some being ovoid or pendant droplets. Larvae at Arapuni from a very dry bank, when placed in a very damp atmosphere, produced vertical lines on which the mucus droplets had run together into larger disorderly droplets which usually sank down to the bottom of the silk thread.

Conditions of Pupation and Possible Phototropism of Adults

In the few cases where pupae or pupal exuviae have been found, it has been stated that the area around at least two inches in diameter is clear of other larvae and their sticky snares. Moreover, the pupa hangs suspended on a long support (Pl. 23, Fig. 2, SU). This would give the imago the opportunity of emerging without being caught by its own, and the sticky snares of neighbouring glow-worms. The larva possibly clears away parts of its own web before pupating. It has been

stated by Hudson, and has been shown by anatomical study in this present paper, that the female adult is able to luminesce for a time at least. The Chief Guide at Waitomo informed the writer that he believed that the female paired during emergence. Though her light shines at this period, there is reasonable doubt if this is done to attract the male, for if he is positively phototrophic, he is then in danger of being snared by the lights of the larvae, which are said by Hudson to glow more brightly. The two females caught at Waitomo did not show a light, and were only seen after a flash-lamp had been directed on to dark walls where they reposed. One of these females, microscopically examined, had paired. It seems possible that both male and female adults may be negatively phototropic, which would keep them clear of snares. Nowhere has the writer seen it reported that moving lights have been observed inside or outside caves where the glow-worms are found. If the female really flies when she is luminiscent, this phenomenon would be likely to have been noted. It is possible that the female remains quiescent and shows her light till she has paired, and then the light fades away. The females caught at Waitomo remained quiet when the light was shone on them, and were easily bottled. They were found on parts of the cave not occupied by larvae. At Waipu several broken pieces of adult male Bolitophila were found stuck on snares. It is possible, of course, that the male is positively phototropic, but generally manages to evade the danger of being snared.

The Suspension of the Pupa.

From Hudson's illustrations, and the flashlight photograph of E. P. Christensen, it is known that the pupa appears to be fixed at the roof by a series of silken threads, which converge to a more solid single cord, which then widens as it reaches the head. From the drawing made by G. V. Hudson's daughter (Mrs. S. Gibbs) in September, 1925, we know that during emergence of the adult from the pupa, the head of the imago is directed downwards, the tail of the pupa pointing slightly upwards, the pupal suspensory cord occupying an intermediate position. When finally clear, the imago stands on the pupal skin with the extremity of its abdomen still within the exuvia, the pupal skin resuming its original vertical position.

In 1886, Hudson drew the pupa with a suspensory cord which he then considered to be a part or extension of the pupal body. His original figure will be found in his “Manual of N.Z. Entomology”, West, Newman & Co., London; this book was written when Hudson was 19 years old, and the Government of the day under Sir Robert Stout directed the purchase of 1,000 copies, both noteworthy events. Hudson, because of the opinions of other entomologists, changed his view, and in his last published “Fragments of N.Z. Entomology”, drew the cord as a silken support, not a part of the pupal body. The cord has also been stated to be the drawn-out mucus platform or tube on which the larva rests.

This question has puzzled the present writer very much. Inspection of Pl. 23, Figs. 2 and 2A, apparently shows that the pupal exuvia is suspended by a cord (SU) which is attached to the front thoracic region at (R) and (RS). In three exuviae found, at Waipu, mounted and examined microscopically, it is impossible to distinguish between the cord (R) and the chitin of the thorax. They are the same colour and merge into each other. It would therefore be natural to assume that Hudson's first view was correct. Against this, however, is the disturbing fact that there is no special area of cells in the correct region of the thorax, in large larvae with imaginal discs. There should be a large stainable area of cells here if such a long cord of chitin were to be produced suddenly as the larva pupates.

Mr. Sear sent the writer a pupa which, unfortunately, had become broken. It was, however, immersed for several days in 5% formalin, and the cord and thorax examined fairly successfully. This specimen shows the cord as formed of separate