36 The American Naturalist. [January, 
shoulder girdle. In regard to these bones Mr. Seeley says: “ If 
the transverse expansion seen in the Paris type of Mesosaurus is the 
‘same bone, its form is imperfect, but it is in the same position as the 
lateral crescentic bone of Stereosternum. There is nothing in the Cape 
Town Mesosaurus which corresponds in form with these bones in 
Stereosternum, and the shoulder girdle in the two types seems to be 
unlike, because the coracoids in the Brazilian genus met (as shown by 
the thickened margin) in the median line, while in Mesosaurus there 
seems to have been a squamous overlap as in Monotreme mammals, 
and as the coracoid cartilages overlap in Triton and Salamandra. 
This condition, so far as I am aware, is not otherwise suggested by 
remains of fossil reptiles. There is also a possible resemblance to Sal- 
amanders in the fact that the scapula and coracoid are not separable, 
though the Cape Town Mesosaurus appears to indicate a suture. ° 
These African Sauromorpha closely resemble some genera from the 
Trias of Europe in general form and characters of the humerus. This 
leads Mr. Seeley to present, for the present, the following classification 
of a small group to which he gives the name “ Mesosauria: ” 
MeESOSAURIA. 
General Characters.—Palate closed in the median line, teeth slen- 
der, prehensile; cervical ribs with a single articulation, dorsal ribs 
articulated to the anterior face of the neural arch. The shoulder- 
girdle formed of scapular and clavicular arches. Humerus expanded 
distally with an ent-epicondylar foramen. Digits terminating in claws. 
Division I. Proganosauria. 
Articular faces of centrum conically cupped, coracoid and scapula 
anchylosed, a larg’: clavicle (or separate episcapule), a sacrum of four 
vertebrz, a foramen in the pubis, five bones in the distal row of the 
tarsus, neck short, tail long. South Africa, South America. 
Division IT. Neusticosauria. 
Articular faces of centrum flat, coracoid and scapula separate, clav- 
icles relatively small (no separate episcapula), sacram unknown, @ 
notch instead of a foramen in the pubis, neck long, tail short. Europe. 
This order is an important diagnostic type of its horizon, and all 
additional knowledge respecting it is welcome. 
Quarterly Jour. Geol. Soc., Nov., 1892. 
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