296 



Shells of the Genus Conus in the Lias. 



I am indebted to the liberality of M. Deslongchamps for 

 the principal drawings. 



Conus cadonensis. Shell smooth, slender, with six or seven 

 volutions and an acuminated spire, posterior edge of each vo- 

 lution carinated, and slightly crenulated. Posterior part of 

 each volution rather concave, and very finely longitudinally 

 striated. 



Fig. 1. 



Fig. I. a. represents an internal cast of a variety with a shorter spire. 

 This cast is still imbedded in the limestone in which it was found. It 

 is regarded as a mere variety of b, because it is well known that in this 

 genus the height of the spire differs greatly in the same species, as for 

 example, in Conus antediluvianus, to which C. cadonensis approaches 

 most nearly. 



Fig. 1. b. A perfect specimen of Conus cadonensis, in the possession of 

 M. Tesson, in which the entire shell is extant. 



Fig. I.e. A magnified representation of a part of the crenulated poste- 

 rior edge of one volution of C. cadonensis. 



Conus concavus. Shell smooth, conical, contracted near the 

 middle, with a concave depressed spire, consisting of nine 

 volutions, each volution carinated at the external edge, and 

 very slightly longitudinally striated. 



Fig. 2. 



Fig. 2. a. A perfect specimen of Conus concavus in the possession of M. 



Tesson, from a drawing by M. Deslongchamps. In this specimen the 



shell itself is extant. 

 Fig. 2. b. represents the concave spire of the same. 

 Fig. 2. c. is a section of the spire, showing the depth of the concavity. 

 Fig. 2. d. A magnified section of a portion of the same, showing the form 



of the volutions. 



