308 DISCOVERY REPORTS 



Body proportions in hundredths of the standard length (70 mm.). Greatest depth of body 24-3 ; 

 length of head 257; horizontal diameter of eye 8-6; length of snout 7-1 ; width of bony interorbital 

 2-6; length of lower jaw 21-4; maxilla 17-8; length from tip of snout to origin of dorsal fin 40 ; snout to 

 adipose dorsal fin 757; snout to pectoral fin 28-6; snout to pelvic fin 47-1; snout to anal fin 61-4; 

 length of pectoral fin 257; length of pelvic fin 12-1 ; length of caudal peduncle 14-3 ; depth of caudal 

 peduncle 9-3. Body compressed; greatest breadth (at pectoral girdle) 14-3. 



Fin-rays. D. 9, A. 21, Pect. 21, Pv. 9. 



Scaling. Large cycloid scales on opercula; probably also present on cheeks. Scales over the trunk 

 and tail well ossified, with a shiny, armoured appearance : cycloid. Scale rows between lateral line and 

 origin of dorsal fin 4; between lateral line and origin of anal fin 7. Number of scales along lateral line 

 (to caudal flexure) 43. Lateral line scales only slightly enlarged, about 1-2 times as deep as those 

 immediately adjacent. 



Vertebrae. 41. 1 



Dentition. About fifty-five small, pointed retrorse teeth on premaxilla. Dentary with about thirty 

 outer, smallish, pointed teeth and 9-10 inner, larger, and depressible teeth of which the second and 

 third are the largest. The first six of these teeth are barbed. Palatine teeth arranged in two closely 

 adjacent rows, each consisting of 5-6 teeth. Lingual teeth ten, the first longest, the rest gradually 

 decreasing in size. 



Text-fig. 1. Scopelarchus cavei. Holotype (x 1-3). 



Colour (in spirit). General body colour yellowish brown, the dorsal surface darker, with a fairly 

 dense peppering of small melanophores covering the upper half of the flank-area above the lateral 

 line. Immediately behind each eye is a black lunate area. Dorsal, anal, pelvic and caudal fins trans- 

 parent or whitish. The pectoral fin is black, except for the two uppermost and five of the lowermost 

 fin rays, which are whitish. 



Underlying the scales over the lower half of the abdomen is a layer of silvery pigment, which extends 

 from the isthmus to the anus. (Is it possible that luminescent tissue may be associated with such a 

 light-reflecting layer?) Above this silvery area, the black peritoneum of the body cavity shows through 

 the body wall. 



This species is most closely related to Scopelarchus guentheri Alcock, but has fewer anal rays 

 (21, cf. 26), fewer lateral-line scales (43, cf. c. 50) and these scales are not enlarged as in S. guentheri. 

 Perhaps there is also a difference in the interorbital width, which in S. cavei is relatively broad, 

 whereas in S. guentheri Alcock (1899) described the eyes as being separated by a 'mere linear 

 space '. 



I have much pleasure in naming this species after A. J. E. Cave, Professor of Anatomy at 

 St Bartholomew's Hospital Medical College. 



1 In all counts of vertebral numbers the last, upturned, caudal element has been included. 



