1877.] ^- J " [Cope. 



ClSTUDO MARNOCHII. 



Represented by the posterior lobe of the plastron of an individual of 

 twice the bulk of the existing North American Cistudos. It is broadly 

 rounded posteriorly, and there is an ernargination at the fenioro-anal der- 

 mal suture. The anterior suture is straight, as is also the lateral, which 

 measures more than a third the length of the entire lobe. On the upper 

 side of the angle included by these sutures is the fossa for fixed attachment 

 with the carapace. The beveled face of the fore edge of the lobe is quite 

 wide. The dermal sutures are well marked. The anal scuta are large, 

 their median length being half that of the lobe. The common femoral 

 suture is only half as long as the ventral. The inferior surface is nearly 

 flat in every direction; and the surface is smooth. The posterior border of 

 the specimen is broken away. 



This species was obtained from the same formation as the last, by Gabriel 

 W. Marnock, to whom I dedicate it. 



Anchybopsis breviarctjs sp. nov. 

 The genus to which the above name was given, was established by the 

 writer in 1870, for a species Cyprinoid fish, from the pliocene formation of 

 Idaho. Its affinities were then stated to be to Albumops (Hybopsis), and 

 related existing genera. The present paper describes two additional spe- 

 cies of the genus, both of which are represented by pharyngeal bones and 

 teeth of both sides. The teeth are shown to be 5-5, in contradistinction to 

 the genera Hemitremia and Albumops, where they are 5-4 and 4-4 respec- 

 tively 



In this fish the common base of the pharyngeal teeth rises upwards, so 

 as to project well in front of the general plane of the bone. The superior 

 teeth are more compressed than the inferior, and the first and second count- 

 ing from below, have convex grinding faces. The pharyngeal bone has a short 

 inferior and a long superior limb. The alate portion is regularly and 

 strongly convex, without abrupt expansion. The nutritive foramina of the 

 anterior face are two large inferior and several small superior ones, 



Measurements. M. 



Vertical extent of bone in a straight line 020 



Width at second tooth 008 



" atfirst " 004 



Length of tooth line 011 



of third tooth 005 



' ' of basal limb to first tooth 009 



This species is of smaller dimensions than the A. latus. 



Anchybopsis altarcus sp. nov. 

 The pharyngeal bones of this cyprinoid are larger and of more slender 

 proportions than those of the A. breviarcus. Specimens from both sides are 

 preserved. The inferior and superior limbs are both elongate, the former 

 slender, the latter fiat. The ala is abruptly expanded at right angles to the 

 long axis ; the external border is thence nearly straight to, and the angle of 



