398 



5. W. WILLISTON 



end is expanded, as in the allied American reptiles. The coracoid 

 lies over the stem of the clavicle, and in all probabiHty is composed 

 of the anterior element only, which is the case with the numerous 

 known scapulae coracoids of Varanoops hrevirostris. The clavicle 

 was represented by Credner as a slender rod, without designation; 

 its shape is like that of Ophiacodon, and it lies in articulation with 

 the interclavicle and the upper front margin of the scapula. I 

 thought that I recognized the usual supracoracoid foramen in the 

 impression of the coracoid, but in this I may have been mistaken. 

 The outline of the coracoid is clearly shown on both sides of this 

 specimen. The outline of the front border of the scapula is also 

 clearly apparent, broadly convex below, gently emarginate above. 



In fact, the structure 

 A / / B , ^^ throughout of the pec- 



toral girdle is like that 

 of Varanoops hrevirost- 

 ris, or as it would be in 

 an immature specimen 

 of that species. The 

 ribs are holocephalous, 

 like those of Ophiaco- 

 don. The humerus in 

 this specimen is turned 

 outward, not inward, 

 and only an entepicondylar foramen is present. There are not more 

 than three pairs of sacral ribs. In much probability the number 

 of presacral vertebrae is twenty-seven, the constant number in the 

 Pelycosauria in the more restricted sense. In brief, Paleohatteria is 

 in every respect a member of the Pelycosauria {sensu latiore), of 

 which it represents a family, Paleohatteriidae (Baur), of co-ordinate 

 value with the Poliosauridae or Sphenacodontidae. 



Pleurosaurus {Acrosaurus) . — This genus has generally been 

 classed with the Rhynchocephalia in the narrow sense, notwith- 

 standing the fact that it has but a single temporal opening, a fact 

 that has previously been known and definitely confirmed by Wat- 

 son. I had the pleasure of studying the excellent material of this 

 genus preserved in the Munich museum, for which my thanks 



Fig. 6. — Paleohatteria longicaudata Credner: A, 

 pectoral girdle, in part; B, left pelvic bones: sc, 

 scapula; c, coracoid; ic, interclavicle; cl, clavicle; 

 il, Uium; is, ischium; p, pubis. 



