Prof. E. D. Cope on the Systematic Relations of Fishes. 157 



present to the recent GanoicTei and Teleostei. I have shared 

 in the doubts occasionally expressed by ichthyologists as to 

 the essential distinction of these latter divisions ; and an ex- 

 amination into the osteology, with reference to this point, 

 confirms the doubts raised by a study of the soft parts. As is 

 well known, Miiller distinguished the Ganoidei by the mus- 

 cular bulbus arteriosus containing numerous valves, and the 

 connexion of the optic nerves by commissure rather than by 

 decussation. He added several other characters, knowing 

 them, however, to be shared by various other orders and sub- 

 classes ; and I have selected the only two which seemed to be 

 restricted to the division. Their restriction to it, however, is 

 only apjiarent ; and Kner points out that the peculiarity of the 

 optic commissure is shared by some Physostomi, and that the 

 difference between the number and character of the valves of 

 the bulbus in Lepidosteus and Amia is quite as great as that 

 existing between Amia and some of the Physostomi. After 

 an examination of the skeleton, it is obvious that in this part 

 of the organism also there is nothing to distinguish this division 

 from the Teleostei of Miiller. It is true that each of the ge- 

 nera referred to it possesses marked skeletal peculiarities ; but 

 they are either not common to all of them, or are shared by 

 some of the Physostomi. If, on the other hand, we compare 

 these genera with each other, differences of the greatest im- 

 portance are observable, which at once distinguish two divi- 

 sions — one represented by Polypterus^ the other by Lepidosteus 

 and Amia. 



In the first place, the basal radii of the pectoral fins of Po- 

 h/pterus are observed to be excluded from articulation with 

 the scapular arch by the intervention of three elements, which 

 form a pedicle or veritable arm for the fin. In Lejndosteus 

 and Amia the radii are sessile on the scapular arch, as in ■ 

 ordinary fishes. The ventral fins present a like difference ; 

 the basal radii are long and four in number in PolyjJterus. In 

 the other two genera they are absent, excepting one rudimental 

 ossicle on the inner basis of the fin (two in Lepidosteus) ^ pre- 

 cisely as in the Physostomous families Mormyridje, Catosto- 

 midas, &c. If we examine the branchial apparatus, Ave find an 

 undivided cerato-hyal, three branchio-hyal arches, and no inner 

 and but two outer bones of the superior branchio-hyals, present 

 in Polypterus. In Lej)idosteus and Amia we have the double 

 cerato-hyal, four branchio-hyal arches, with four outer and four 

 superior elements, characters of the typical Teleostei. The 

 maxillary bone of Polypterus^ instead of being free dis- 

 tally, as in fishes generally, is united with an cctopterygoid 

 and with bones representing, in position at least, postorbital 



