SYSTEMATIC REVISION %'] 



occupies the entire width of the bone; it narrows with the shaft downwards 

 and the borders rise, one more than the other. The two join in a strong 

 protuberance, which looks directly backwards, and may be called for the 

 present the third trochanter. The shaft is keeled below and in continuation 

 of the trochanter, to where it expands for the distal articular extremity. 

 The latter looks partly downwards, and is divided by a deep groove above 

 into two parts representing the usual condyles. One of these is compara- 

 tively depressed, while the other has a massive superior crest, which makes 

 its long axis vertical instead of horizontal, as is that of the other condyle." 

 Below are given the original descriptions of Epicordylus and Rhachitomus : 



Char. Gen.: " Epicordylt(s is known from a large part of the vertebral 

 column, including all the regions excepting the cervical, so far as at present 

 appears. In general the vertebrae resemble those of Clepsydrops, having 

 well-developed intercentra. The diapophyses are at the base of the neural 

 arch, and are prominent, and with large undivided articular extremity; 

 they are not present on the caudal vertebrae. The neural spines are com- 

 pressed below and enlarged transversely above, so as to be claviform. They 

 are not elongated over the lumbar or sacral regions, but are similar to those 

 of the dorsal vertebrae at those points. The ossa ilii resemble those of Clepsy- 

 drops. The zygapophyses are as usual oblique upwards and outwards, and 

 the centra are not shortened." 



Char. Specif.: "The centra area little compressed, and higher than wide. 

 In the anterior caudal region they are a good deal more compressed. The 

 intercentra in a part of the dorsal series are larger than in any known species 

 of Clepsydrops. The neural spines are bilobed at the apex on the sacral 

 region, and become shortly bifurcate on the caudal series. 



"Measurements. 



M 



"Length of a series of seventeen dorsal vertebrae 0.610 



Length of an anterior neural spine 050 



Length of posterior 070 



Length of tubercular costal face of anterior dorsal 020 



Length of tubercular costal face on seventh vertebra of the series 



from the last 035 



Length of five caudal vertebrse of probably the same animal 180 



Elevation of fourth caudal neural spine 057 



Width of neural spine at summit 035 



Length of ilium 120 



"This species appears to have been about the size of the Mississippi 

 alligator. Unfortunately the cranium is unknown, but probably some of 

 the jaws and teeth in my possession belong to it." 



Rhachitomus: 



"Each vertebra consists of two segments, an intercentrum and a neural 

 arch. The true centrum is wanting in the specimens at my disposal, and the 

 intercentrum supports portions of two adjacent neural arches. With these 

 it shares the intervertebral articular face usually borne by the centrum. 

 Each articular face is thus divided into three portions, one-third belonging 

 to each neurapophysis and one-third to the intercentrum. Between these 

 the course of the chorda dorsalis is unobstructed. Neural spine present 

 coossified. Diapophysis large, with a subvertical tubercular costal face, 

 Zygapophyses well developed. 



