CARBONIFEROUS CBPHALOPODS. 



339 



slender and tapering. The nodes are less prominent in M. quadrangularis 

 and these disappear in adults, in which also the shell is thinner than in Wal- 

 cotti. We have had the type of this last mentioned species for examina- 

 tion through the kindness of Prof. Newberry. 



Fig. 38. 



Metacoceras Hayi, n. s. 



Loc. Kansas. 



Coll. R. Hay. 



Figs. 38, 39, natural size. 



This cast has broad flattened sides, having angular umbilical shoulders 

 where the sides descend abruptly to the umbilici. There is an outer row of 

 tubercles on the edge of the abdomen. These are elongated longitudinally 

 and the depressions between them are often very distinct; the surface of the 

 cast is otherwise smooth. The sutures have short and very broad lateral 

 lobes with saddles at the umbilical shoulders and on the abrupt edges of the 

 abdomen. The abdominal lobe is short and broad. It has a slight angle or 

 V-shape in the specimen, but this is probably due to compression. The su- 

 tures just inside of the umbilical shoulders appear to be nearly straight on the 

 nearly vertical narrow zones on either side of the outer whorl, but there is 

 probably a shallow dorsal lobe on the impressed zone. The living chamber 



