DIPHYABYLA HUBRECHTI. 231 



still attached, and for this reason is included here as probably belonging to the 

 latter species. Most likely it represents a case where the changes in form, out- 

 lined above, have been delayed. Bedot does not state whether he observed 

 more than one such specimen. 



B. bassensis is known to occur very generally throughout the Mediterranean 

 and Tropical Atlantic, the Malaysian region, the Eastern Tropical Pacific, 

 and it is recorded from off the southeast coast of Australia (Bass Straits) and 

 from south of Tasmania. I can find no record of it from the Indian Ocean, 

 but it may be expected to occur there, and thus to parallel Abylopsis tetragona (p. 

 220) in its distribution. 



DIPHYABYLA Lens and Van Riemsdijk, 1908. 



This interesting genus is so far known from only one species, D. huhrechti 

 Lens and Van Riemsdijk, founded for a single specimen in the "Siboga" col- 

 lection, and represented by a second rather better preserved example in the 

 present series. 



Diphyabyla hubrechti Lens and Van Riemsdijk. 



Plate 12, fig. 7. 



Diphyabyla hubrechti Lens and Van Riemsdijk, : OS, p. 36, p\. 6, fig, 47. 



Station 4683, 300 fathoms to surface; 1 anterior nectophore, 7 mm. long. 



The nectophore agrees in shape with the account by Lens and Van Riems- 

 dijk, who have called attention to the essential similarity in external form 

 between this species and Abyla leuckarti. The most interesting feature of 

 Dyphyabyla is the apical projection of the nectophore in a narrow pyramidal 

 form. And it was the consequent external resemblance to the Diphyids which 

 suggested the generic name. This external modification obscures its close rela- 

 tionship to A. leuckartii; but when the ridges and facets are analyzed their 

 fundamental unity is at once apparent. Lens and Van Riemsdijk have given 

 such an extended and complex discussion of the two that the following summary 

 of the superior nectophore will suffice here. In Diphyabyla there are four ridges 

 at the pointed apex, two dorsal, and two ventral. The two dorsals run direct to 

 the base, enclosing a triangular dorsalfaeet. Each of the two ventrals branches 

 dichotomously at the level of the apex of the nectosac, so that from this point 

 downward, there are two ventrals, and a lateral on each side running without 

 further subdivision to the base, though the ventrals reach the base together, 



