i8o 



depressed. The depth of the trunk diminishes but little back- 

 wards, and is contained thirteen and a half times in the total 

 length without caudal; the length of the head is one-sixth 

 of the total. Head broad, much broader than deep, its greatest 

 depth being two-thirds of its length. Snout broad, much depres- 

 sed, with obtusely rounded anterior profile; cleft of the mouth 

 very wide, the maxillary moderately dilated behind and exten- 



Fig. 70. Ipnops tmtrrayi Gthr. Head from above and below (after Giinther). 



ding beyond the middle of the length of the head. Mandible 

 projecting beyond the upper jaw, broad, but owing to the 

 depressed form of the snout its outer surface is nearly entirely 

 at the lower side of the snout. Infraorbital chain of bones 

 very narrow, wedged in between the transparent lamina and 

 the maxillary, with four very distinct apertures leading into 

 the mucous duct. The upper surface of the head, including 

 the snout, is wholly covered by the two cornea-like laminae 

 of the luminous apparatus. They are closely attached to each 

 other along the median line, each being divided by a shallow 

 transverse ridge into a larger anterior and a smaller posterior 

 portion. The ridge turns forward near and parallel to, the 

 median line, and marks the course of a superficial mucous 

 duct. The gill-laminae are well developed and the gillrakers 

 long, needle-shaped, closely set, about twenty-two in number 

 on the outer branchial arch. 



The vent is nearly twice as distant from the root of the 

 caudal fin as from the end of the snout, and rather more 

 than the length of the head from the gill-opening; it is placed 

 between the ventral fins. The dorsal fin commences immedia- 

 tely behind the vertical from the vent; it is short, but its 

 longest rays are twice as high as the body. Origin of the 

 anal midway between the vent and the root of the caudal, 



