No external cementurn layer, caudal vertebrae biconcave, and brim 

 narrow. Fore limbs large and massive. 



The teeth of this genus resemble those of Hadrosaurus, and like 

 them, are replaced from the " front," an arrangement which pre- 

 cludes the possibility of more than one series of teeth being in 

 functional use at one time. The robust fore limbs and elongate 

 ilium distinguish Diclonius from Hadrosaurus. From Trachodon 

 it differs in the absence of the rough cementurn layer on the back 

 of the tooth. 



Char. Specif. — The faces of the teeth are acuminate oval in form, 

 and are divided by an elevated keel, which is median above, but 

 turns to one side at the base. Margin crenate, the grooves ex- 

 tending more or less on the convex "back," which is otherwise 

 smooth. 



Sacrum with ten vertebrae, the last centrum much compressed, 

 the diapophyses extending horizontally from the neural arch 

 above, and connected by a vertical lamina with the iliac supports ; 

 length 27.33 inches. The bones of the limbs are robust, the hinder 

 the longer, but not so much so as in some other genera. Length 

 of femur 22 inches; width, proximally, 7.4 inches; distally 6 inches. 

 Length of tibia 20 inches; greatest diameter, proximally, 8 inches; 

 distally 7.25 inches. The three antei'ior dorsal vertebrae are co- 

 ossified, and the first exhibits a deep cup for articulation with the 

 preceding vertebra. The episternum is a T-shaped bone, thin and 

 keeled on the median line below. Length of transverse portion 

 21 inches. 



Paronychodon lacustris, Gen. et sp. nov. 



Char. Gen. — The teeth which characterize this genus have the 

 genera] character of those of Plesiosaurus, Elasmosaurus, etc. 

 The crowns are subconic, and the enamel is thrown into longitu- 

 dinal plicae. The special characters of the genus are seen in the 

 form of the crown, one side of which is convex, and the other side 

 plane, so that the section instead of being circular is semicircular. 

 It is also strongly curved in the direction of its plane face. 



Char. Specif. — Both anterior and posterior edges are curved, 

 and are not acute nor denticulate. There are four plicae on the 

 flat face, only two of which approach the apex. There are six 

 keels on the convex face, all of which approach the apex. All 

 the carinae are rather obtuse, and the enamel is otherwise smooth. 

 The apex is very acute. 



