103 



has the shape of a long and narrow wedge ; it does not form 

 a very close articulation with the dentary. The dentary is 

 long and comparatively slender, has a rounded outline, and is 

 occupied by an external row of large, and an internal band of 

 small teeth. The mandibular teeth, like those of the upper 

 jaw, are somewhat different from the teeth of A.calva; they 

 are shorter, stouter, and are not so much incurved or recurved. 

 They are very sharp, and show a constriction below the apex. 

 The small teeth are of the usual size and shape. , The jugular 

 plate is well developed, and is long and narrow. The hyoid 

 arcli is very much the same as that shown in the recent 

 species ; the characteristic flat branchiostegals are well 

 marked ; they appear to be thirteen in number. 



The scapular arch is long and stout. The clavicle is 

 strongly bent, the supra-claviclc is short, and the post-clavicle 

 is long. The pectoral fin is too indistinct for description. 



The vertebra are of considerable depth in the anterior 

 dorsal region, and decrease steadily in size as they go back- 

 wards. The neural spines are long and slender, and project 

 strongly backwards. The relation of the centra to the 

 arches seems to be about that seen in A. calva, but the neura- 

 pophyses are more slender. The diapophyses are long and 

 slender, in this respect differing from the Bridger species and 

 approaching the modern one. The dorsals are thirty-five in 

 number. The caudals number about forty-seven. They 

 have smaller centra, but longer and stronger neurapophyses 

 than the dorsals. The haemal arch is long, and the hasma- 

 pophyses articulate movably with the centra. The spines 

 supporting the caudal fin rays are very stout. The dorsal fin 

 is long and soft, and has long interneurals supporting short 

 rays; these are fifty-three in number. The anal fin, on the 

 other hand, is very short, having but nine rays, which are long 

 and jointed, and articulate with short interhaemals. The cau- 

 dal fin appears to be of the usual form. The femur is of the 

 general shape characteristic of Amia, but is not just like that 

 of A. calva. It is shorter, broader at the proximal end, while 

 the distal end is narrower, and has a deeper constriction just 

 above it. The ventral fins are placed under the middle of the 

 dorsal region, and have each ten rays. The scales are of the 

 usual cycloidal shape, and minutely striate. 



