3!!^ S A U R I A. 



stage between a completely hidden auricular aperture and a perfectly 

 visible one, sometimes on the right, at others on the left side, and 

 also on both sides, on the same specimen. Moreover, P. platyrhinum, 

 which has permanent auricular apertures, is congeneric with P. modes- 

 turn and Anota mccalli, as shown further on. 



The genus Phrynosoma is, truly speaking, an American type of 

 Saurians. The geographic distribution of its species reads, thus far, 

 as follows : 



1. Phrynosoma. orbiculare,— in the Yalley of Mexico. 



2. Phrynosoma hernandesi, — in Western New Mexico and Sonora. 



3. Phrynosoma ORNATissiMUM,^in the eastern mountainous regions of New Mexico. 



4. Phrynosoma brevirostrum,— in the plains of Kansas and Nebraska. 



5. Phrynosoma douglassi, — in the mountainous range from Puget Sound to the 

 Colorado Desert, embracing the Valley of the GIreat Salt Lake of Utah. 



6. Phrynosoma coronatum,— in Upper California; west of the Eocky Mountains. 



7. Phrynosoma cornutum,— in Texas, from the Gulf of Mexico to the mountains of 



New Mexico. 



8. Phrynosoma regale,— in the Valleys of the Zuni and Colorado Rivers. 



9. Phrynosoma mo'calli, — in the Colorado Desert. 



10. Phrynosoma platyrhinum,— in the Valley of the Great Salt Lake of Utah. 



11. Phrynosoma modestum,— in the Valley of the Rio Grande del Norte (Rio 

 Bravo). 



Thus, making eleven species with which we are thoroughly ac- 

 quainted. Those which have been mentioned or described under 

 the names of Phrynosoma hufonium, P. harlani, P. wiegmanni, P. 

 UainviUei, P Solaris, and P planiceps, are mere synonyms, which will 

 be found under their proper headings. 



There are various characters according to which the above species 

 may be subdivided into minor groups. If the position of the nostrils 



