APPENDIX. 



DESCRIPTION OP A MUGILOID FISH FROM THE MESOZOIO STRATA OP 



COLORADO. 



SYLLAEMUS, Cope. 



Allied to the Mugilidce. — A short, spinous, dorsal fin; ventral fins abdo- 

 minal, posterior to the spinous dorsal. Pectoral fins subinferior in position. 

 Coracoid bones forming- a compressed, keeled body. Scales large, cycloid ; 

 lateral line present, extending along the middle of the sides. Parietal 

 bones less than epiotics, entirely separated by the supraoccipital. Frontal 

 bones large, wide ; their common suture distinct. 



The opercular apparatus extends obliquely backward, while the man- 

 dible is produced forward ; hence the inferior part of the hyomandibular 

 and the symplectic are directed obliquely forward. The end of the muzzle 

 is broken off, but the posterior part of the dentary bone does not exhibit 

 any teeth. The opercular bones are thin, and their inferior borders reach 

 the median line of the inferior side of the head. 



The only species of this gemts which has fallen under my observation 

 is represented by a specimen in which the body posterior to the femoral 

 bones is wanting. The surface is covered with scales, so that only the out- 

 lines of the femoral bones can be distinctly seen. These are thickened and 

 curved outward; those of opposite sides are well separated from each other. 

 The scales exhibit a very delicate concentric line sculpture. 



The very posterior position of the ventral fins distinguishes this genus 

 from Mugil, while the inferior position of the pectoral fins is not seen in 

 Atherina. The lateral line does not occupy the inferior position seen in the 



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