156 PROCEEDINGS OF THE ACADEMY OF [1883. 



The minute first tooth is generallj^ found in small specimens, but 

 not always. It lingers in some to middle size. This species has 

 not been found in the Oregon basin. The settlers call the 

 pharyngeal bones " baby-jaws." 



LEUCUS Heckel. 

 Fifche Syriens, 1843, p. 48. Anehybopais Cope, Proceed. Amer. Philos. Soc, 1870, 



p. 543. 

 LeuCUS latUS Cope. Anchyhopais lafuK Cope, 1. c. 



Much the largest species of the genus, as yet only represented 

 b}^ two pharyngeal bones of opposite sides. Southern Idaho. 

 Leucus condonianus Cope, sp. nov. 



This fish is represented b}^ four pharyngeal bones, two of each 

 side, which have the dental formula 2"5-5-2 ; the presence of the 

 two inner teeth being doubtful on one of those of the right side. 

 The}' indicate a smaller fish than the L. altarcus, and one about 

 the size of the Ceratichthys biguUatus. The teeth display but little 

 grinding surface, and have swollen subconic crowns, which are 

 less expanded transversely than those of the L. altarcus. The 

 style is moderately long and not much recurved. The external 

 aliform border is rather full, and expands graduall}' from the 

 style, not abruptl}', as in L. altarcus. It is especially full oppo- 

 site the supei'ior extremity of the tooth series, where it is con- 

 tracted in L. lafus. 



Measurements of Medium Size. M. 



Length on tooth line, '014 



Length of tooth line, "007 



Length of apex from tooth line, .... "005 



Width at middle, -005 



Dedicated to Professor Thos. Condon, of Eugene, Oregon, who 

 first discovered and explored in part, the fossiliferous formations 

 of the Oregon and Idaho basins. 



SQUALIUS Bonap. 

 Jordan emend. PtycJiochilua Ag&ss. Clinoslom ii8 Girsbrd. 0/("(/ofee?»s Cope, Proceeds. 

 Amer. Philosoph. Soc, 1870, p. 540. 



The American species generally diflfer from the t3^pe in the 

 reduced number of teeth in the right phalangeal series. The 

 dental formula is 2-5-4-2, in our extinct and recent species. In 

 the pliocene species here noticed, the teeth have acute, slightly 

 incurved, apices. They diflfer from each other as follows : 



