74 MEMOIRS OF THE CARNEGIE MUSEUM 



asper spinosus 



Length of head 27 27.5 



Diameter of eye 10 11 



Width of snout at nostrils 8 6 



Length of maxillary 15 17 



Greatest depth of body 24 27 



Dorsal rays 12 14 



Anal rays 18 19 



Pectoral rays 16 15 



Scales in lateral line 39 39 



In D. asper, the head is but Uttle narrowed anteriorly, the upper orbital 

 margins are nearly parallel, and the snout is high and bluntly rounded, pro- 

 truding a trifle on the level of the nostrils. In D. spinosus the head narrows 

 rapidly forward, the orbital naargins strongly converge, the snout is not bluntly 

 rounded and protrudes farthest at the premaxillaries. 



In D. asper, the gill-rakers are somewhat shorter and heavier, 5 + 10 or 

 5 + 11 in number; in D. spinosus 7 + 16. 



In D. spinosus, each scale covering a photophore of the ventral series 

 develops long slender spines many times larger than those on neighboring scales. 

 These are specially developed along the base of the anal fin, where the spines 

 overlap and form a dense band. No such enlarged spines are present in D. 

 asper. 



Brauer finds the eye smaller than heretofore given for D. asper, but in 

 adults it is but little less than two-fifths the length of the head, and is pro- 

 gressively smaller in the young. 



Photophores. — The superior preorbital is usually concealed, but the inferior 

 is conspicuous. The suprapectoral is higher than in D. spinosus, constantly 

 nearer the lateral line than the base of the pectoral. From the first to the 

 fourth, the thoracics form two evenly diverging lines, the fifth far out at the 

 sides, opposite the outer ventral ray; the spacing of the pairs is nearly equal, 

 the interval between third and fourth pairs shortest. Supraventral midway 

 between lateral line and base of ventral (not nearer lateral line as in Brauer's 

 figure). First pair of ventrals fully exposed, the two covered by a single much 

 enlarged scale of the median series, in addition to the small special scales thus 

 wholly overlapped; second pair somewhat farther out at the sides, forming with 

 the third and fourth two lines gently converging backwards; the four pairs 

 are equally spaced. Supra-anals in a very blunt angle, the anterior obliquely in 

 front of and below the second. The upper is immediately below the lateral 



