Salmopercas and Other Transitional Groups 243 



short dorsal has two or three spines, there are two or three 

 spines in the anal, and the abdominal ventrals are opposite 

 the dorsal. Allied to Eris- 

 matopterus is Amphiplaga of 

 the same deposits. 



We cannot, however, feel 

 sure that these extinct frag- 

 ments, however well preserved, 

 belonged to fishes having an 

 adipose fin. Among spiny- 

 rayed fishes the Percopsidce 

 alone retain this character, and 

 the real affinities of Erisma- 

 topterus may be with Aphredo- 

 deridcB and other percoid 

 forms. 



The relations of the extinct 

 family of Asineopida are also 

 still uncertain. This group 

 comprises fresh-water fishes 

 said to be allied to the Aphre- 

 doderidce, but with the pelvic 

 bones not forked. Asineops 

 pauciradiata, squamijrons and 

 viridensis are described from 

 the Green River shales. With 

 Erismatopterus all these fishes 

 may belong to the suborder 

 of SalmoperccB, but, as above 

 stated, the possession of the adipose fin, the most characteristic 

 trait of the Salmoperccs, cannot be verified in the fossil remains. 



Suborder Selenichthyes, the Opahs : Lamprididae. We may bring 

 together as constituting another suborder certain forms of uncer- 

 tain relationship, but which seem to be transitional between 

 deep-bodied extinct Ganoids and the forms allied to Platax, 

 Zeus, and Antigonia. The name of Selenichthyes (a-rf\rfvr), moon ; 

 ix^vs, fish) is suggested by Boulenger for the group of opahs, 

 or moonfishes. These are characterized by the highly com- 

 pressed body, the great development of a large hypocora- 



J. 194. Shoulder-girdle of the Opah, 

 Lampris gttttatus (Briinnich), showing 

 the enlarged infraclavicle. (After 

 Boulenger.) 



