Geological Papers. 127 



and flat and are nearly in a transverse line. The zygosphenes, a 

 remarkable peculiarity characteristic of this genus, and in a lesser 

 degree of Crossotelos, are well developed, though the surfaces are 

 much smaller than the zygopophysial ones. The peculiar linear 

 striations, quite characteristic of the genus, are visible on all parts 

 of the vertebra, though less pronounced on the transverse processes. 



EXTREMITIES. 



It is somewhat remarkable that evidence of the appendicular 

 skeleton has hitherto never been furnished by the numerous speci- 

 mens of Dlplocaulus which have come to light from Texas, Illinois 

 and Oklahoma. It has, in consequence, generally been assumed 

 that the creatures were legless and snake-like in shape and wholly 

 adapted for aquatic life. Jaekel several years ago suggested the 

 presence of limbs in Dlplocaulus, because of the well-developed 

 clavicalar girdle, evidence of which was presented by Broili. That 

 Dlplocaulus did have limbs, both anterior and posterior ones, al- 

 beit reduced, is now abundantly demonstrated by the material col- 

 lected the past season in Texas and Oklahoma for the University 

 of Chicago. Among this material there are one complete coracoid, 

 five humeri, seven femora, numerous ends of epipodial bones and 

 four associated metapodials. The mesopodials were doubtless un- 

 ossified. 



It is a well-known fact that specimens of land vertebrates 

 in the Texas Permian are apt to be more or less intermingled, 

 and the association of limb bones, especially when isolated, is 

 by no means positive proof that there was an anatomical asso- 

 ciation in life. When the fauna of the Texas beds is suffi- 

 ciently well known to eliminate in large part the known from the 

 unknown, the detection of such accidental intrusions will be a much 

 easier matter than it is at present. Many specimens are found ex- 

 posed and weathered and more or less broken ; in the collection of 

 such upon the slopes and in the gullies it may often happen that 

 fragments from different horizons* are found intermingled ; in other 

 cases bones of different individuals may actually be associated in 

 the same matrix. In the present case the association of the limb 

 bones with the various specimens is such as to convince the most 

 skeptical of their anatomical relationships. The material of Dlplo- 

 caulus at present in the University collections is as follows : 



Specimen No. 610. Skull nearly complete — the nasal extrem- 

 ity, the extremities of the horns, and much of the palate missing; 

 fourteen probably consecutive vertebrae, including the axis and 



