1883.] NATURAL SCIENCES OF PHILADELPHIA. 159 



One of these lacks the style, and the other the apical portion. 

 The species differs from the D. macrodon in the flatter apical ramus, 

 which is devoid of the marginal tuberosity' and distal recurvature, 

 seen in that species. It is straight and forms an acute angle with 

 the axis of the tooth series. The style is short, stout, and some- 

 what recurved. The marginal ala is rather abruptly given off oppo- 

 site the second tooth from below. The necks of the pharyngeal 

 teeth are contracted, so that the internal and external outlines of 

 the crown are convex. The grinding surface is quite oblique. 



. -013 

 . -010 

 . -005 

 fish. From Southern 



Measurements. m. 



Length of tooth line, -014 



Length of apical ramus, 



Width of bone at middle, 



Width of crown of tooth, 

 This species was about the size of the gold- 

 Idaho, J. L. Wortman. 



CATOSTOMID^. 

 Catostomns shoshonensis sp. nov. 



Of this fish I have two crania from the Idaho basin, one 

 obtained by Mr. Wortman and the other by Mr. Clarence King. 

 Two other crania, collected by the same gentlemen, represent a 

 variety, or possibly another species. 



The bones of the skull are relatively more elongate than those 

 of the C. labialus. The width of the superior surface of the 

 parietal bones between the lateral angles is equal to two-thirds 

 the length of the superior surface of the ethmoid bone posterior 

 to the base of its anterior spine. The two measurements are 

 equal in the C. labiatus. The ethmoid has three median longi- 

 tudinal concavities and raised borders in the C. shoshonen.ns, but 

 is regularly convex in the C. labiatus. The temporal fossa is 

 separated by a narrow raised band from the pterotic fossa in the 

 former, but by a very wide band in the latter. The supratemporal 

 crests are not raised and sink gradually to the level opposite the 

 posterior part of the supraorbital border. There is a slight 

 median frontal keel which extends forwards from the same point. 

 The frontoparietal fontanelle is well defined, elongate, and rather 

 narrow. It commences at the base of the supraoccipital spine 

 and extends to opposite the anterior foramen of the postfrontal 

 bone. The bones of the skull are smooth. 



