GEMPYLIDAE, LEPIDOPIDAE AND TRICHIURIDAE 19 



siderable distance; suborbital ring not complete, and without a sensory 

 tube; pelvic bones represented by a pair of long, simple rays lying 

 free just beneath the skin remote from the shoulder girdle ; no abdominal 

 hasmal arches present; small, slender parapophyses present on last 

 two vertebrae; a sharp keel running along side of vertebras for nearly 

 whole length of vertebral column; body not incased in rays of bone, 

 and only four or five epipleurals present anteriorly. 



TRICHIURIDAE (Trichiurus) 



Skeleton differing from Lepidopus in having no pelvic bones (not 

 represented in all Lepidopidae) ; in having the tail taper to a point 

 which is without hypural bones or caudal fin; and in having the weak 

 anal reduced to short, stiff spines. 



In the following descriptions the osteology is given in detail. 



PROMETHICHTHYS. 



A specimen of P. prometheus from the Canary Islands, 17 inches 

 in length. 



The cranium is elongate and the preorbital portion is somewhat 

 produced. The crests and ridges on the superior surface form a com- 

 plicated pattern, but in general resembling those of Scomber, having 

 an oblique ridge from the supraoccipital against which the temporal 

 and pterotic crests stop. This ridge is forked in front of the temporal 

 crest, and the inner branch runs forward to the ethmoid, while the 

 outer reaches the edge of the cranium above the front of the eye. The 

 myodome opens through a round foramen posteriorly. The occipital 

 region is not produced as in Scomber. 



The exoccipitals meet broadly over the basioccipital, and have 

 large condyles overhanging the latter. The supraoccipital extending 

 down over the suture between the epiotics and the upper part of the 

 exoccipitals appears from the exterior to separate them, though both 

 the epiotics and exoccipitals meet for their full length within the cranium 

 as in the Scombridae. 



The supraoccipital crest is but little developed. It is considerably 

 behind the eye and not very far anterior to the occipital condyle. It 

 is not formed at all by the frontals anteriorly, and scarcely rises above 

 the level of the temporal crests. It has no sharp apex directed upward 

 as in Lepidopus. 



