DISCOSCAPHJTES. GON1AT1TES, ETC. 221 



Subgenus Macroscaphites, Meek. 



Shell with inner turns merely in contact, or so slightly embra- 

 cing as to leave a very large, shallow umbilicus; periphery 

 rounded; body portion much extended from the inner volutions ; 

 surface costate. S. GIUAS, Sowb. 



Subgenus Discoscaphites, Meek. 



. Shell with general outline subeircular or slightly oval, and 

 generally much compressed ; inner volutions forming a large 

 part of the entire bulk, and so deeply embracing as to leave only 

 a small umbilicus; body portion so short as scarcely to become 

 tVee at the aperture, flattened on the periphery; surface orna- 

 mented with costtv, and provided on each side with from about 

 four to nine rows of tubercles, the outer of which are largest 

 and arranged along each margin of the periphery. SCAPHITES 

 (V)NRADi. Morton. 



h. Shell differing from the last chiefly in having the volutions 

 so narrow and little embracing as to leave a large, shallow um- 

 bilicus, and the body-volution deviating very little from the 

 regular curve of the others. S. (AMMONMTES) TIIEYENNENSIS, 

 Owen. 



(Joins GONIATITES, DeHaan. 



Shell spiral, discoidal; sutures of septa lobed ; siphuncle 

 dorsal. 



About 200 species. Upper Silurian to Triassic. Europe. 

 (J. HENSLOWI. Sowb. PI. 100. fig. 512. Garb, limestone. Me 

 of Man. 



(U-nus CERATITES, DeHaan. 



Shell spiral, discoidal; slightly involuted whorls, generally 

 strongly sculptured; sutures crenulately lobed, toothed at base. 



Twenty-nine species. Devonian Chalk. Europe, India. 

 (\ NODOSUS. Brug. PL 100, fig. 516. Muschelkalk. Wurtem- 

 berg. 



Genus BUCHICERAS, Hyatt. 



Founded on the cretaceous species of Ceratites, which differ 

 >in the triassic forms in the characteristics of the sutural out- 

 les : they are not Geratites at all, but, strictly speaking, Am- 

 lites. They show this in the form of the abdominal cell in 



