Distribution.

Amphipholis squamata is believed to be the only ophiuroid with a world-wide distribution. It appears to vary but little, and in examples taken from the coastal rock-pools of Cook Strait, New Zealand, I have found no obvious difference in form or habit from those inhabiting the waters of Britain, twelve thousand miles distant.

Now, the existence during development of a free-living larval stage in many marine animals has been used as a means of explaining the wide distribution of some species. It is argued by this theory that while in the free-living planktonic stage a species may be carried over distances impossible for it to cover when in the adult, bottom-dwelling stage. In a communication to me, my friend, Mr. J. E. G. Raymont, of Edinburgh University, has pointed out the discrepancy between this theory and the distribution and life-history of Amphipholis; for although Amphipholis squamata has the most widespread distribution of any ophiuroid, yet it lacks a free-living larval stage, while other ophiuroids with a more restricted distribution possess well-developed larvae. The adult Amphipholis squamata is a typically littoral form, never extending below 125 fathoms (Mortensen, 1927).

In view of its strictly littoral distribution, the presence of the species in New Zealand is of the greatest interest, seeing that as it lacks a pelagic stage it can only have reached that country by way of shallow seas which no longer exist in the area. It occurs in South America, and Mortensen (1924) records it from the Sub-antarctic Auckland Islands. This distribution argues strongly in favour of the theory held by many biologists of the former existence of a land-