i6o University of Texas Bulletin 



Leonard formation of the Glass Mountains and the Mt. Ord range 

 of Brewster County, West Texas. The geniis seems to be represented 

 by numerous specimens wherever it appears. White says that he 

 found about forty specimens at the MiHtary Crossing of the Big 

 Wichita River, Baylor County. In the Glass Mountains we have 

 collected in a short time about fifty specimens in one very limited 

 locality, and we found them numerous wherever the genus was re- 

 presented, with exception of only one place, where not more than two 

 specimens could be found; although the locality was extremely rich 

 in brachiopods. In west Texas, Perrinites so far seems to be limited 

 to only one horizon, the Leonard' formation,-*^ while in the horizon 

 above it, the Word formation, Waagenoceras appears. In north 

 Texas it is probably also limited to a certain stratigraphical zone al- 

 though appearing in two petrographical subdivisions; at least, J. P. 

 Smith remarks that P. Hilli was found associated with Popanoceras. 

 Medlicottia and other forms possibly identical with those described 

 by Dr. Chas. A. White from the Clear Fork division. This would indi- 

 cate that the faunas of the Clear Fork and the lower part of the 

 Double Mountain formation are similar and belong to stratigraphical 

 zones not very different in age.^ 



We may add that J. P. Smith presumed, when he established his 

 genus Shumardites, that the Cyclolobinae wert . ."erived from this 

 genus. As we shall show in the description of P. vidriensis n. sp, this 

 species develops on very small whorls a suture (pi. X, fig. 20) which 

 in general corresponds to that of Shumardites which proves that J. 

 P. Smith was entirely right. Perrinites certainly is derived from 

 Shumardites. 



It may be remarked here that the Waagenoceras Cmnminsi var. 

 Guadalnpensis described by Girty^ certainly does not belong to Perrin- 

 ites. It may perhaps, represent several species of Waagenoceras or 

 even of diflferent genera. The very imperfect illustrations do not allow 

 a full recognition of its shape and the form of the sutures. We shall 

 discuss this species in our paragraph on Waagenoceras. 



'I have lately seen some ammonoids from the Delaware beds which seem to belong 

 to Perrinites with respect to their form, but the suture could not be made visible. 

 ''Compare Appendix to this work. 

 "Girty, Guadalupian Fauna, p. 502, pi. 29, fig. 23-26. 



