MALACOPTERVCill 



553 



Pectorals low down, folding like the ventrals. Post-temporal 

 forked ; the upper branch attached to the epiotic, the lower 

 to the squamosal ; no post-clavicle ; coracoids forming together 

 a ventral keel ; scapular foramen between scapula and clavicle ; 

 pterygials well developed, three in contact with coracoid. Ven- 

 trals with 7 rays. Branchiostegal rays in moderate number (8 

 to 10). Air-bladder communicating with the ear. Xo oviducts, 

 the eggs falling into the abdominal cavity before exclusion. 



Fig. 333. — Upper (A) and posterior (B) views of skull and pectoral arch of Hyodon alosoides 

 (the supratemporal removed oa the left side), bo, Basioccipital ; cl, clavicle ; cor, 

 coracoid ; eo, exoccipital ; eot, epiotic ; eth, ethmoid ; /, frontal ; m, maxilla ; mcor, 

 mesocoracoid ; it, nasal ; oo, opisthotic ; ^^, parietal ; pd, postclavicle ; pm, prae- 

 raaxilla ; por, praeorbital ; pif, postfrontal ; ptr, pterygials ; pits, post-temporal ; 

 scl, supraclaviole ; so, supraoccipital ; sor, suborbital ; sq, squamosal ; ste, supra- 

 temporal. 



Elongate, compressed, silvery Fishes, covered with moderate- 

 sized cycloid scales ; head naked ; mouth large, with strong den- 

 tition ; gill-openings wide; dorsal fin short, posterior to the 

 ventrals ; anal rather elongate ; caudal well developed, forked. 



A single genus {Hyodon) with three species CMoon-Eyes of the 

 Americans), all reaching the length of about a foot, inhabiting 

 the fresh waters of North America east of the Kocky Mountains. 



