UPPER TRIASSIO SPECIES. 107 



von Buch's terms superior-lateral, lateral, inferior-lateral, and auxiliary lohes 

 and saddles. The former method seems to me more simple, and enables one 

 to refer very precisely and directly to any particular lobe or sinus, whether 

 there be few or many. For the ridges crossing the volutions, Professor 

 Hyatt uses the term, pilce; while I have used for the same the old term coste. 

 I am not, however, objecting to Professor Hyatt's terminology, which 

 is very good, but merely explaining the different terms we have here and 

 elsewere used for the same parts of the shell. 



-CLYDONITlDiE.* 



"Genus COROCERAS, Hyatt. 



" («<5p5f, a helmet; Kepag, a horn.) 



^^ Ammonites, Goniatites, Aganides, &c. (sp.), of several authors, but not as those genera 



are now restricted. 

 '■'■ Clydonites (pars), Hauer (1860), Sitzungsb. der Kais. Akad. Wiss., XLI, 122. — Laube 



(1869), Fanna St. Cass., 14. 



" This genus comprises the following species, viz., Clydonites delpJiino- 

 cephalus, C. ellipticus, Hauer, and C. nautilinus and C. monilis, Laube; the lat- 

 ter being viewed as the type. These species all have numerous lobes and 

 cells, with smooth sutures, and a large abdominal lobe ; the latter being very 

 broad and prominent. They are pileately ribbed and very involute ; the 

 umbilicus nearly covered. The mouth is more or less hooded or constricted. 

 These are the only members of the group that can be satisfactorily charac- 

 terized. The remaining species originally included in Clydonites are very dis- 

 tinct from the typical forms and from each other, and may be arranged into 

 the following groups: 



" 1. — Clydonites genuculatus, C. glaucus, and C. Eryx, Hauer, with C. 

 Wissmanni, of the same author. 



" These have a similarly short clumpy abdominal lobe, with a minute 

 siphonal cell; but otherwise they are entirely different. The whorls of the 

 first, however, are short, with gibbous sides, subangular at the edge of the 

 abdomen; the second, high and crowded Those of C. glacialis, on the 



* Professor Hyatt proposes this new family for the reception of his above described 

 genus Coreceras and Clydonites, Hauer, with probably other genera not contained in 

 the Nevada collections. In the same way he proposes other new families farther on. 



