166 ARTHUR WILLEY. 



the vicinity of Noumea, New Caledonia, belonged to P. flava. 

 Franjois^ simply mentions that his native servant one day 

 brought him some fragments of a Balanoglossus, and he makes 

 no further reference to it. 



1 have found a Ptychodera which may probably be identified 

 with P. flava, especially if it may be assumed that Eschscholtz's 

 figure represents approximately the natural size of the object,^ 

 in great abundance near the low-tide mark on the small islet 

 of Amedee, upon which stands the lighthouse, some twelve 

 miles out from Noumea and eight or ten miles inside of the 

 great Barrier Reef of New Caledonia. 



It occurred near the surface of the sand, chiefly underneath 

 loose stones, often adhering to the latter, and creeping into 

 the holes with which the coralline blocks are riddled. On a 

 later occasion I found it to be, if possible, still more abundant 

 on the rocky platform of coral limestone which surrounds a 

 great part of the Isle of Pines. This platform is, in places, 

 much excavated, and, while it is exposed at low water, there 

 are numerous rock-pools scattered over it, in some of which 

 many diff'erent kinds of seaweeds luxuriate. In the shallower 

 pools Ptychodera flava occurs in great numbers in the sand 

 at the base of or in the neighbourhood of the tussocks of sea- 

 weed, being often involved in the roots of the latter. Several 

 species of Nemertines occur in the same locality,^ but are 

 much rarer than the Ptychodera. 



External Features (cf. Fig. 1). 

 "When first taken from their native liabitat the individuals 

 of P. flava average in length approximately from 1^ to 2 or 

 even 3 inches, and the intestine is often full of sand. But 



^ Ph. Fran9ois, " Glioses de Noumea," ' Archives de Zool. exper.* (2), t. ix, 

 1891, p. 232. 



2 Spengel (loc. cit., p. 190) suspects that the figure given by Eschscholtz 

 represents the animal on a reduced scale. Judging by the material obtained 

 by me in New Caledonia, this need not have been the case. 



^ The exact spot on the Isle of Pines where I found the Ptychodera was 

 situated at the point on the opposite side of the harbour to that on which 

 the military buildings are placed. 



