32 U.S. NATIONAL MUSEUM BULLETIN 284 



plate and are loosely attached in a band of connective tissue. The 

 teeth of the dental plate do not directly contact the bone of the 

 dentary. There are about seven interrupted horizontal series of 

 replacement teeth embedded in the connective tissue of the dental 

 plate ventroposterior to the functional series of teeth. In addition 

 to the teeth of the dental plate, each dentary bears a large recurved 

 canine implanted on the bone dorsolaterally. There is a large fossa, 

 open posteriorly, in the dentary beneath each of these canines. 

 Completely contained in each of these fossae, there is another 

 (replacement?) canine tooth. The contained canine was not found 

 in any of the other specimens of E. nigricans examined. 



A large posterior pocket in each dentary allows for insertion of 

 the anterior portion of its respective articular. A circular opening 

 to the pocket is present posterolaterally in each dentary. There 

 are several fine, short spurs on the anteromesial surface of each 

 dentary. 



Hygmandibular and palatine arch (figs. 1, 3, 7). — Each hyo- 

 mandibular bears two condylar surfaces dorsally. The anterior 

 articulates with a fossa formed by the sphenotic and prootic and the 

 posterior articulates with a fossa in the pterotic. On the internal 

 surface of each hyomandibular between and just below the condylar 

 surfaces, there is a small opening that leads into a ventrally extending 

 canal (for the n, truncus hyomandibularis) that exits on the external 

 surface of the hyomandibular near its ventro-anterior margin. 

 Dorsoposteriorly on each hyomandibular, there is a third condylar 

 surface that articulates with the opercle. The dorsal end of each 

 preopercle lies just external to this condyle on its respective hyo- 

 mandibular. A posteroventrally directed blade of each hyomandibular 

 overlaps its respective preopercle dorso-anteriorly. The anteroventral 

 portion of each hyomandibular is thickened into a supporting rod 

 that is capped with cartilage and is attached ligamentously to the 

 cartilaginous dorsal ends of its respective symplectic and interhyal. 

 The dorso-anterior end of each hyomandibular overlaps and is 

 attached to the dorsal end of its respective metapterygoid. The 

 anterior margin of each hyomandibular is broadly attached liga- 

 mentously to the posterior margin of its respective metapterygoid. 



Each broadly crescentic symplectic attaches along its ventral 

 third to its respective quadrate in a groove on the quadrate's inner 

 surface. 



Each palatine bone consists of a ventroposterior shank and an 

 anterodorsolaterally extending arched arm. The mesial surface of 

 each palatine shank closely joins the ventrolateral surface of its respec- 

 tive ectopterygoid. The posteriormost end of the shank attaches in a 

 notch near the ectopterygoid 's posterior end. The mesial surface of the 



