PHYLOGENY OF FUSUS AND ITS ALLIES. 95 



however, the nodules disappear after a while and the keel or carina 

 alone remains. In old individuals the keel may disappear, this portion 

 of the whorl having- the characters of the typical form of the species. 

 Localities: This and the succeeding- varieties are found in great 

 abundance in the vicinity of Bordeaux, and in the Vienna Basin. The 

 detailed localities are given below. 



The Typical Form of the Species. 

 (Plate VIII, fig. 6; also figs. 7, 8.) 



Basterot's original description is as follows : 



"F. testa transverse prcssc lineolata, lineis insequalibus ; anfractibus 

 superioribus solum plicatio, subtuberculatis." 



In this form the keel is lost early, the last whorls of the conch being 

 rounded in contour. In some specimens the keel is not at all developed, 

 and the rounded whorls follow immediately upon the subangular 

 ribbed whorls. Spirals are very numerous, increased by intercalation, 

 which becomes prominent in the fifth whorl. 



Var. MAJOR Grateloup (fig. 7). 

 (Plate VIII, fig. 22.) 

 "Anfract. carinatis ad medium subnodosis." (Grateloup.) 

 This variety is large and robust. Following the tuberculated stage 

 a carina appears on which spines of moderate strength are formed. 

 These are of the type found in Fiilgur carica, though they are not so 

 pronounced as in that species. Some of the specimens of this variety 

 have a striking resemblance to species of Fulgiir from the American 

 Tertiary this resemblance being due, however, to parallelism and not 

 to genetic relationship. These spines appear in some specimens after 

 the disappearance of the tubercles, and the formation of the carina stage 

 (PI. VIII, fig. 8). They thus indicate a distinct line of development 

 for this variety. 



The relations of these varieties may be expressed as follows : 



var. major. F. burdigalensis 



(typical). 



var. carinata. 



I 

 var. tubcrculosus. 



A form identical with Basterot's typical form was figured by 

 Grateloup under the name var. siibkczigata with the following de- 

 scription : " Testa minorc fragile laevigata." 



There is some variation in die slenderness of the species, but most 

 individuals have a strongly convex or bulging body-whorl. All speci- 



