46 



THE VOYAGE OF H.M.S. CHALLENGER. 



Cerebratulus macroren, n. sp. (PI. I. figs. 13, 14, 18, 19 ; PI. X. figs. 8, 9 ; PL XL 

 fig. 11 ; PI. XII. figs. 1, 2,7,8; PI. XIII. figs. 7-9 ; PI. XIV. figs. 7, 8, 11 ; 

 PL XV. figs. 2, 3, 19). 



From Japan, at Statiou 232a, a Sehizonemertean has been brougLt home by the 

 Challenger Expedition, which I was first inclined to regard as identical with Cerebratulus 

 parkeri, but which I have reluctantly been obliged to distinguish S2:)ecifically — reluctantly, 

 because there being no possibility of giving outwardly visible distinctive features of 

 colour or shape, I must indicate an anatomical difference as the principal point of 

 distinction between the two ; and all the more reluctantly because of a second specimen, 

 which, dredged at 700 fathoms oft' New Zealand (Station 169), was identical with the 

 Japan specimen, and difi'ered from its much closer geographical neighbour in this very 

 same point. I could not, however, evade assigning the latter sj)ecimen to the species 

 now about to be described, knowing by experience that if the confusion created by the 

 unnecessary multiplication of s^iecimens is often very troublesome, the premature com- 

 bination under one name of forms that afterwards may be showTi to be different is often 

 quite as apt to lead to inextricable confusion, when characters which, as a matter of fact, 

 only belong to one of them, are attributed to both. 



About this second specimen M'Intosh's rough notes contains the following passage : — 

 " A small Lineus, presenting the ordinary external characteristics, and of a dull 

 yellowish hue, somewhat brownish on the dorsal surface in front. It was tapered from the 

 snout backwards. The cutis has a simple areolar structure ; the gelatinous contents were 

 slowly extruded in the sections after mounting, as cylindi'ical or clavate, translucent gela- 

 tinous processes. The basement tissue is largely developed as a translucent belt all round." 

 Of the larger specimen from Japan, the head is figured (PL I. figs. 18, 19). The 

 cephalic slits are perhaps comparatively a little longer than are 

 those of Cerehratulus parkeri (PL XV. fig. 5), although the New 

 Zealand representative (PL I. figs. 13, 14) is again very similar, 

 even in this respect, to Cerehratulus parkeri. 



The internal anatomical character, to w^hich I alluded just now 

 as being a distinctive feature, by which the species differs from 

 Cerehratulus parkeri, is the size of the longitudinal nephridial 

 ducts, which are exceptionally conspicuous (both in the Japanese 

 and in the New Zealand specimens), and which have their deferent 

 ducts leading to the exterior situated at the very hindmost end, 

 whereas in Cerebratulus parkeri there are two deferent ducts, the 

 one situated very closely behind the other, and placed about the 

 midtUe region of the longitudinal canal. The accompanying wood- 

 cut diagrammatically illustrates this difference between the two species. Oudemans 

 (loc. cit.) has already demonstrated that the number of deferent ducts to the nephridial 



Fig. 4. — Neplaridial ducts 

 and theii" commuuication 

 with tlie exterior. «, for 

 Cerebraluhis parkeri ; b, for 

 Cerebralulus macroren. 



