34 Mv. R. Valleiitin on the 



tached to the isthmus ; four gills with narrow lamlnte and 

 scabrous clavate gill-rakers, which, to the number of about ten, 

 are a little elongated on the outer side of the first arch ; no 

 pseudobranchiffi. 



Body and head, including the glosso-hyal region and the 

 branchiostegal membranes, covered with deciduous membra- 

 nous cycloid scales of moderate size. 



The scales of the very conspicuous lateral line are adherent 

 and greatly enlarged ; they lie beneath a continuous sheath of 

 black skin, which is loopholed over a long narrow groove 

 wath raised margins situated along the vertical diameter of 

 each scale. These grooves are filled with an opaque white 

 substance, wliich probably has a luminous function. The 

 lateral line, in fact, is exactly similar to that of several species 

 of Halosaurus. 



The dorsal fin, which begins jast in advance of the gill- 

 opening, and the anal, which begins almost a head-length 

 behind the same level in the adult, are confluent with tlie 

 pointed caudal. The narrow, pointed pectorals are as long as 

 the rostrorbital portion of tlie head. There are no ventral 

 fins whatever. 



■ The stomach is siphonal, with a bulbous pyloric end ; the 

 intestine, which is very long, is looped and coiled, the loops 

 being held by a stout mesentery ; there are six small casca in 

 a semicircle round the pylorus ; no air-bladder can be detected. 



Colours in the fresh state uniform jet-black. 



Two females, 15"5and 11*75 inches long respectively, from 

 Station 112, 561 fathoms ; a third specimen from Station 116, 

 405 fathoms. 



This extraordinary form seems almost entitled to rank by 

 itself in a separate subfamily of the Ophidiidge. In general 

 appearance and in most of its structural details it has the 

 closest resemblance to the ty|3ical Brotulina ; but it differs 

 from them all in its remarkable HQlosaurus-Yv\.Q lateral line 

 and in the entire absence of ventral fins. 



[To be continued.] 



III. — Notes concerning the Anatomy of certain Rotifers. 

 By Rupert Vallentin. 



[Plates IV. & v.] 



It was originally my intention to prepare for publication a 

 series of papers concerning the anatomy of some of our larger 

 species of common Rotifers whose structure I had been able 



