![Thumbnail: [Volume 79, 1951 page 541]](/journals/rsnz/images/rsnz_79/thumbnails/rsnz_79_03_0760_0541_ac_02.gif)
Internal Anatomy (Plate 105, fig. 2)
Septum vi/vii is slightly thickened and muscular and the septa vii/viii, viii/ix, ix/x, x/xi, xi/xii, xii/xiii and xiii/xiv are greatly thickened and strongly muscular. Narrow longitudinal muscle bands pass through the coelom and join the septa vi/vii to xiii/xiv. The last oleven septa of the body are also much thickened and muscular.
Alimentary Canal. The pharynx occupies segments i–iv. There is a short, thin-Walled proventriculus in v and a very thick-walled muscular gizzard in vi. The oesophagus extends from vii to xvi and there are no oesophageal glands. The intestine commences in xvii.
Vascular System. The dorsal blood vessel is unpaired throughout its length. A slender supra-intestinal vessel lies immediately under the dorsal blood vessel and extends through segments x–xiii. Four pairs of dilated hearts, a pair in each of x, xi, xii and xiii arise from the supra-intestinal vessel.
Reproductive System. There are two pairs of small lobate testes, a pair in × and a pair in xi, attached to the anterior septum of the segment close to the ventral midline. The two vasa deferentia of each side remain separate, but lie close together as they pass along the ventro-lateral aspect of the peritoneum to their point of entry into the prostatic duct. The paired ovaries are attached to the anterior septum of xiii in a similar position to the testes. The ovaries are very thin transparent laminar organs with the ova arranged like strings of
![Thumbnail: [Volume 79, 1951 page 542]](/journals/rsnz/images/rsnz_79/thumbnails/rsnz_79_03_0761_0542_ac_02.gif)
beads along the lamina. There is a single pair of spermathecae in ix. Each consists of a large ovoidal sac opening by a wide duct to the exterior. A thick digitate diverticulum opens into the spermathecal duct just below the spermathecal sac. (Plate 105, fig. 3.) The prostates are convoluted tubular organs arising from a thick muscular duct in xvii and following an irregular course to their termination in xxi. A sac containing penial chaetae lies against the medial aspect of each prostatic duct and is attached by strong muscle fibres passing through septum xvii/xviii to their insertion on the dorso-lateral aspect of the peritoneum close to the posterior septum of xviii. The penial chaetae have slender gently curved shafts and a slightly recurved blunt tip. Distally, for about a third of their length, they are armed with rows of minute spines which point towards the tip of the chaeta (Plate 105, fig. 4.) There are two pairs of botryoidal vesiculae seminales, a pair in xi and a pair in xii, surrounding the oesophagus in those segments.
Meganephridia are present in every segment except the first. The tubules are very slender and at first sight it appears that there are both meganephridia and micronephridia present in each segment. However, close examination shows that the meganephridium consists of three distinct parts:
| (i) |
A slender tubule arises from the small nephridial funnel and passes down the lateral margin of the coelom to |
| (ii) |
a complex coiled tubular portion of the nephridium close to the ventral nerve cord. Here the tubule is thrown into a series of tightly wound spirals which project into the coelom and superficially closely resemble micronephridia. |
| (iii) |
The tubule passes from the coiled portion straight back up the lateral aspect of the peritoneum to open to the exterior through a very small vesicle which is little more than a slight bulb in the end of the tubule. |
Remarks. The species is most closely similar to R. edulis, but the spermathecae of R. edulis are in viii, while those of R. intermedius are in ix.
Rhododrilus disparatus (Plate 106, figs. 1–3)
Several specimens of this large sienna-brown earthworm were collected from unmelanised sands in a recent flood deposit beside a small stream three miles south of Tolaga Bay and others from a silt loam under native rain-forest (ngaio, titoki) ten miles east of Otoko on the Gisborne-Opotiki road.
A mature specimen measures 197 mm, in length and 6 mm. in diameter and has 203 segments. It is sienna-brown dorsally, paler ventrally, and has a greyish-brown clitellum, covering xiv–xviii and part of xiii down to the level of chaeta a (5 ½ segments). The prostomium is epilobous. There are eight chaetae per segment, arranged in pairs. On xxiv:
ab = cd = lmm.; aa = 2 mm.; bc = 2·5 mm.; dd = 4 mm.
There is a single pair of small spermathecal pores at 8/9 in line with chaeta b. A pair of female pores occurs on xiv, slightly anterior to chaeta a. The single pair of prostatic pores are situated on the apices of a pair of prominent dome-like papillae, in line with the chaetae ab
![Thumbnail: [Volume 79, 1951 page 543]](/journals/rsnz/images/rsnz_79/thumbnails/rsnz_79_03_0762_0543_ac_02.gif)
on xvii. Male pores are not visible externally. The nephridiopores are in a single series anterior to chaeta c, commencing on ii.
Prominent paired tubercula pubertatis occur in line with the chaetae ab at the posterior margins of segments ix and x, and in the intersegmental grooves 19/20, 20/21 and 21/22.