INVERTEBRATE PALAEONTOLOGY. 



421 



specimen represented on our plate, it will be found to agree more nearly 

 with the Wyoming examples, than would appear from the figure of the 

 former as worked out of the matrix ; at least, a very critical examination 

 shows that its costa.* do bifurcate even, as far as they can be traced around 

 the sides of the inner part of the volution, as in the Wyoming specimens; 

 while the larger ones on the other parts of the body, also, were pinched up, 

 as it were, around the sides, and bifurcate and give off lateral divisions, so 

 that the whole, including intercalated ones, all appear of more nearly uniform 

 size on the periphery than represented on our plate. 



The following cuts of one of the Wyoming specimens are given for com- 

 parison with the type of <S'. Warreni. 



Fig. 61. 



Fig. 03. 



Fig. 62. 



Scaphites Warreni, var. Wyominycnais. 

 Fig. 01. A peripheral view, natural size. 

 Fig. 62. A side-view of the same specimen. 

 Fig. 03. A septum of same, magnified about two diameters. 



From these cuts it will be seen that the Wyoming shell, making due 

 allowance for the condition of the type-specimen of <S. Warreni, and some 

 defects in the figure of the same given on our plate, agrees pretty nearly, 

 though we yet know nothing of the nature of the septa in the latter. 



It will also be seen that the Wyoming form agrees very closely with 

 the well-known European S. aqualis of Sowerby. Indeed, it resembles that 

 shell so nearly that I have sometimes been strongly inclined to regard it as 

 only a variety of the same, even after a direct comparison with European 

 specimens of Sowerby's species. 



Sowerby's specimens of his species were imperfect, and did not show 

 the termination of the lip; nor do Mantell's figures of the same (given by 

 him under the names S. costatus and S. striatus) show the lip; but the 

 latter author describes one of his supposed species as having the aperture 

 " margiuated." D'Orbigny also both figures and describes French exam- 

 ples of S. eequalis as having a thickened rim around the margin of the lip. 



