146 Memoirs of the Indian Museum. [Voiv. II, 



Colour black. 



One specimen measuring 13 cm. from the Bay of Bengal. Station 371, 500' 

 fathoms. Registered No. '^^^^. 



This genus must be closely related to Platytrodes. It is most interesting that 

 the two genera should be separated by such a major character as a pair of pelvic fins 

 and yet resemble one another so closely in minor details. The similarity of their 

 outward appearance is most remarkable. 



The genus P/fl/y^foc^ßS contains the species P.apus, Günther, and P. procerus, 

 Brauer. The " Investigator " has obtained a single specimen of P. a^ws from near 

 the Laccadive Isles. I have had the opportunity of comparing this with Platytroctegen. 

 The main difference lies in the pelvic fins of the latter. With this is necessarily asso- 

 ciated the fact that the contours of the body are not formed by empty skin as in 

 Platytrodes , for pelvic fins could not be supported on a fold of empty skin. In Platy- 

 trodes the highest and lowest quarter of the body will transmit light, for the com- 

 ponent layers of skin are in contact with one another internally. In our specimen of 

 P. apus only those scales which cover the empty folds of skin are keeled. The scales 

 covering the middle or thick part of the body are not keeled. 



The specimen of Platytrodes apus obtained by the '' Investigator " has a tubular 

 papilla behind the operculum similar to that possessed by Platytrodegen. In both 

 the system of muciferous canals on the head is as alike as though they were of the 

 same species. Similarity in other features is equally great and yet the differences are 

 very decided. Apart from the pelvic fins the following are the chief differences : — 



1. The triangular cranium is depressed in the middle line in Platytrodes apus, 



— nearly flat in Platytrodegen. 



2. The scales are keeled like those of a reptile in Platytrodes apus, — smooth 



in the other. In our specimen of P. apus only the upper and lower scales 

 are keeled. 



3. The remarkable clavicular spine is bifid at the tip in Platytrodes , — simple in 



the other. 



4. The dorsal and anal fins are longer in Platytroctegen. 



P. procerus is also furnished with the postopercular papilla. It is likely that the 

 first example of P. apus which was taken by the " Challenger " in the Atlantic Ocean 

 also possessed a similar organ which became detached or was otherwise overlooked. 



Alepocephalus microlepis, sp. nov. 



Illustr. Zool. ''Investigator,'' Fishes, plate xliv, fig. 4 (190g). 



B. 6, D. 20-22, A. 30-33, V. 5-6, P. 10, L.l. 125, L.tr. 30-35. 



The head is slightly less than, a third of the total without the caudal. The maxi- 

 mum height — which is at the base of the pectoral fin — is a sixth of the total. The vent 

 is nearer to the gill-opening than to the base of the caudal fin. The ventrals are 

 much nearer to the vent than to the gill- opening. The anal fin, being much longer 



