1880.] 57 [Cope. 



No indications of dorsal fin are to be found in the specimen, and those 

 which exist must originate behind a point above the base of the venti'al 

 fins. The pectoral fins originate further behind tlie head than is usual. 

 The ventrals are well posterior, and close together. 



The skull is transversely fractured at the coronal suture, as I suppose it 

 to be, which divides the front, just anterior to the point of attachment of 

 the hyomandibular bone. At the anteroexternal angles of the parietals, are 

 distinct post-frontal bones of a sub-triangular form, which send a process 

 posteriorly from their external angle. The hyomandibular presents a nar- 

 row convex external edge, and is directed backwards ancl downwards. It 

 leaves a wide space posterior to the postorbital bones. Of the latter there are 

 two, the inferior connected with the front of the orbit by a single wide, 

 suborbital bone. The orbits are as much lateral as vertical, and are in 

 front of a transverse line dividing the skull equally. The muzzle is 

 broadly rounded, and is covered with rounded plates of ganoine. Several of 

 these have median perforations. The opercular apparatus is obscured by 

 matrix in the specimens ; a small bone lies on the inferior part of the sus- 

 pensorium on both sides, and may be the preoperculum. The top of the 

 head behind the muzzle is entirely without ganoine layer in two speci- 

 mens ; its surface is smooth, or weakly finely ridged. On the other hand, 

 the premaxillary, maxillary, mandibular and gular bones are invested 

 with perfectly smooth ganoine. 



The pectoral fins are quite wide, and their rays diverge exclusively from 

 the inner border, and are very fine. The axial portion is thick and acu- 

 minate, and has no fulcra on the external edge, but is covered with quad- 

 rate and rhomboidal scales, of very much smaller size than those of the 

 body. The axial portion of the ventral fins is not quite so large as that of 

 the pectoral. 



The scales of the body are quite large and overlap each other by both 

 the free edges. Though their form is rhombic, the apex is rounded. The 

 surface is ganoid, and entirely smooth. There are five rows between the 

 internal -bases of the ventral fins, and twelve between the external bases of 

 the pectorals. The gulars of the posterior pair are about as long as those 

 of the anterior. There are anteriorly one and posteriorly two rows of 

 plates between the anterior gulars and the mandible. 



This fish was probably three feet in length. 



Measurements. M. 



Length of head to base of first distinct lateral body scale 



(posterior border of skull damaged) 161 



Length to base of pectoral fin 180 



" (axial) to canthus oris 077 



" of skull to coronal suture 067 



" " " anterior border of orbit 031 



Width " at " " " 065 



" of front between '' " " .j 036 



" " at coronal suture 039 



PROC. AMER. PHILOS. SOC. XIX. 107. H. PRINTED JUNE 33, 1880. 



