390 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



This species was referred by me to the genus Lwlaps provisionally, 

 as no characters could be discovered in the mandibular ramus and teeth ^ 

 the only portions in my possession which indicated a genus distinct from 

 those already known. I have since received from Mr. Lucas a femur 

 and other bones from the locality from which the jaw and teeth were 

 derived, which is appropriately proportioned to them, and in other re- 

 spects similar to the corresponding parts of other carnivorous Dinosauria. 

 A comparison with the femora of Lwlaps and Megalosaurus shows that 

 the carnivore of the Dakota Eeptilian fauna can be referred to neither 

 of these genera. Its characters are as follows : — 



Head flattened and transverse. Great trochanter not produced to the 

 head, prominent, and terminating in a free apex. A considerable third 

 trochanter on the posterior inner side of the shaft. Condyles very con- 

 vex, moderately produced, separated by a well-marked trochlear, and 

 deep popliteal grooves; surface not pitted. An epicondylar projec- 

 tion on the interior side of the internal condyle. 



In the compressed and transverse head this genus agrees with Lcelaps,. 

 but the internal epicondylar tuberosity is not found in that genus. The 

 distal extremity of the femur rather resembles that of Megalosaurus, 

 which, according to Owen, presents the tuberosity in question. This 

 genus has, however, according to the same author, a round head, so as 

 to be quite distinct from that of this form. From the other Dinosauria 

 of the Dakota, whose femora are known, which belong to the genera 

 Camarasaurus and AmpMccelias, the internal epicondylar enlargement, 

 or rather the contraction of the internal condyle, readily separates it, as 

 well as the larger third trochanter and flat head. 



In specific characters, this femur is intermediate between the Megalo- 

 saurus bucMandii and the Lwlaps aquilunguis. The shaft is straight,, 

 moderately robust, and with a transversely oval section. 



Brachyrophus altarkansanus, gen. et sp. nov. 



Char. gen. — These are exhibited in vertebrse of the amphicoelous type, 

 with the articular concavities rather shallow, and the centra not short- 

 ened. What is probably a dorsal vertebra is shorter than those of more 

 posterior position. None of them display hypapophyses, or any other 

 apophyses or costal articular surfaces. A remarkable character of the 

 genus is the shortness of the pit-like facet for the attachment of the 

 neurapophysis. It is relatively longer on the anterior vertebra, while 

 on the posterior vertebrae it occupies little more than one-third the 

 length of the centrum, those of the opposite sides approaching closely 

 the middle line. Tissue of the centra rather coarsely spongy. 



This genus presents characters different from those of any Dinosau- 

 rian or Crocodilian with which I am acquainted. The neural arches 

 being lost, some important indications are wanting. 



Char, specif. — The concavities of the articular faces of the vertebrg& 

 are somewhat unsymmetrical, having one or more fossse at or near their 



