No. 440.] 



STUDIES OF GASTROPOD J. 



simple ribs and simple spirals, after which the shoulder flattens 

 out and the ribs become faint toward the suture. An angulatior 

 appears on the whorl, formed at first by two strong spirals, but 

 later, the upper becomes strongest and causes the formation of 

 rather flattened blunt serrations. Intercalated spirals appear on 

 the sixth whorl. 



This shell, though much smaller than the Fulgurs, has all the 

 characteristics required for an immediate ancestor. It must, of 

 course, be separated from Lcvifusiis pagoda, I leilprin, and I pro- 

 pose to designate it Lovifusus ? harrisi, after Professor Gilbert D. 

 Harris, whose indefatigable labors in the Tertiaries of the Gulf 

 region have brought together a wealth of material which may 

 serve as a basis for further phylogenetic study. Both Dall and 

 Harris consider Levifusus in the line of ancestry of Fulgur ; the 

 latter, indeed, regards L. pagoda Heilprin as the prototype of 

 the Fulgurs. The protoconch of the ordinary form of L. pagoda 

 does not satisfy the conditions of such an ancestor, but that of 

 the Texan form does. Whether or not these two types are to be 

 considered congeneric remains to be determined ; further investi- 

 gation mav show that the changes from a normal naticoid type of 



Fulgurs, the similarity of forms in both cases being explainable 

 as an instance of parallelism. " Fusus" quercollis Harris from 

 the Midwav stage, and "Fusus" rugatus Aldrich from the 

 Lignitic, seem to be related to the ancestors of Fulgur. These 



