33 



forwards of the corona between the eyes; from the apparently world-wide serratodentata it 

 differs in nothing but the (presumably) smooth jaws, of which however nothing is stated in 

 Conant's description beyond their number. It is often extremely difficult to detect the serrations 

 in specimens in which it is poorly developed, when the head is (as often) under the prepuce; 

 and it is quite possible that Conant may have overlooked them. But until hispida has been 

 re-studied in American waters, it must stand as a valid species. 



It seems hardly probable that Aida really had Conant's species before him. Not only, 

 as already pointed out, are the numbers of teeth against this identification, but his figure differs 

 markedly from Conant's ; it shows a marked neck, quite unlike the strong collarette of hispida ; 

 the anterior fin is widest at about the middle of its length, instead of being widest posteriorly; 

 and the posterior fin is about equally distributed on trunk and tail, instead of being much 

 more on the tail than on the trunk. 



Doncaster also records hispida from the Maldive Islands. It is to be hoped that 

 reporters on the next Indo-Pacific collections will consider the possibility that hispida Doncaster 

 may = neglecta Aida (with which the short description closely tallies), and that hispida Aida 

 may = robtista Doncaster. But it is of course also possible that I have confused hispida with 

 robusta or with ferox in the Siboga collections. 



Sagitta lyra Krohn. 



A. Krohn. Op. cit., p. 272. 



A few specimens with this label were received from the Zoological Station in Naples. 

 I still think that this species is probably furcata Steinhaus, (compare Biscayan Plankton, p. 64), 

 altered by pressure in the tow-net or by the action of reagents, or by both, in a manner which 

 is familiar in several of the more flaccid species {furcata, hexaptera, enflatd). But on spirit 

 material it is impossible to feel positive on the point. 



Krohnia foliacea Aida. 



T. Aida. Op. cit., p. 19. 



Characters (deduced from the describer's text and figure). Head small. Body thickest 

 in the middle third, tapering evenly backwards and forwards. Longitudinal muscles thick. Tail 

 nearly 20 per cent, of the total length. 



Lateral fins long, from about the middle of the caudal segment to the front of the 

 abdominal ganglion. 



Jaws with the tips curved as in hamata. Corona ciliata 'flask' shaped, on the head only. 



Formula 11 : 20 : 7 : 5. 



But for the short tail and few posterior teeth, this might easily enough be young hamata, 

 from the cold water which is stated in some years to reach comparatively low latitudes on the 

 coast of Japan during the period of the N.E. Monsoon. It may yet prove to be so, for the 

 posterior teeth, although too few for the hamata of the area studied by the Siboga Expedition, 

 are not too few when compared with specimens from the Faeroe Channel. 



SIBOGA-EXPEDITIE XXI. tj 



