THE OSTEOLOGICAL CHARACTERS OF THE SCOM- 



BROID FISHES OF THE FAMILIES GEMPYL1DAE, 



LEPIDOPIDAE AND TRICHIURIDAE. 



BY EDWIN CHAPIN STARKS. 



The descent of the family Trichiuridae from the Gempylidae through 

 the Lepidopidse was long ago pointed out, and the following results of 

 an osteological comparison between these families only go to strengthen 

 the evidence in favor of this relationship, though the descent is not 

 in a direct line, if we can take Promethichthys as a typical representative 

 of the family Gempylidse. 



Promethichthys is more closely related to Scomber than to any other 

 existing genus of the family Scombridse, or at least Scomber has retained 

 more ancestral characters of Promethichthys than any other member of 

 its family has. These two genera are alike in the character of the 

 cranial crests; in having the opisthotic at the lower surface of the 

 cranium not separating the exoccipital from the pterotic; the subor- 

 bital ring complete and bearing a sensory tube ; and the caudal peduncle 

 without a lateral keel. 



That Lepidopus and Trichiurus did not come, however, directly 

 from Promethichthys, but from some form that has begun to develop 

 in the direction of Scomberomorus, is shown by the opisthotic interposed 

 between the exoccipital and the pterotic, and the incomplete suborbital, 

 ring and sensory tube. This ancestor may have been Gempylus, a form 

 I have been unable to obtain, but showing a development towards the 

 elongate forms of Lepidopus and Trichiurus. 



In view of the extremely close osteological resemblances between 

 the families Lepidopidse and Trichiuridaj it is with much hesitation 

 that the former family is recognized here. The former family differs 

 from the latter chiefly in the possession of a caudal fin, but when it is 

 considered that this fin, in Lepidopus, though well developed, is not 

 very strongly supported, and being at the end of a long, weak, ribbon- 

 shaped body, is probably of little assistance, its loss does not appear 

 of great importance. 



(17) 



