332 University Geological Survey of Kansas. 



him. I have been able to examine some of the detached ver- 

 tebrae from near the head, and so far as I can judge the sides of 

 the neural arches do not differ materially from those farther 

 back in the column. 



The abdominal cavity is short, with well-developed ribs. The 

 caudal fin is not well preserved in any of the specimens, only 

 the bases of the rays being present. On one of the slabs there 

 are a number of small rays and other fragments just back of 

 the abdominal cavity, which is probably a portion of the pelvic 

 fin. ■ The rays are small and have no great length. The pec- 

 toral rays are also rather delicate and curved near the proximal 

 extremity, while near the middle portion and distal end they 

 are cross-segmented. Along the back there are numerous dermal 

 plates, the most of which have no characteristic markings. 



The known American species are : 



Empo nepceollca Cope, Niobrara Cretaceous, western Kansas. 

 Empo semianeeps Cope, Niobrara Cretaceous, western Kansas. 

 Empo contracta Cope, Niobrara Cretaceous, western Kansas. 

 Empo merrilli Cope, Niobrara Cretaceous, western Kansas. 

 Empo lisbonensis Stewart, Fort Pierre Cretaceous, western Kansas. 



Empo nepseolica. Plate LIX. 



Empo nepazolica Cope, Proc. Am. Phil. Soc. 1872, p. 347; Cret. Vert. 



West, p. 230. 

 Empo sulcata Cope, Hayden's Bull. U. S. Geol. Surv. No. 2, p. 46. 

 Cimoliehthys sulcatus Cope, 1. c, p. 351. 



This species is represented in our collection by the remains 

 of several individuals, among which is a skull almost complete, 

 from which a fair idea of the anatomy of this portion can be 

 gained. 



The bone described and figured by Cope as a premaxilla has 

 since been shown to be a palatine by specimens in the British 

 Museum which have the maxillae and premaxillse in place. 

 The bone is elongate and curved longitudinally, and at the an- 

 terior extremity there is a rostrum-shaped apex of dense bone 

 which projects forward beyond the last tooth. On the superior 

 border there is a slight crest of bone, which probably serves to 

 loosely connect this portion to the skull. The teeth are arranged 

 in two series. At the anterior extremity there are several large 



