52 TRANSACTIONS OF THE WAGNER FREE 



37 ; also illustrated by him in ' Fossils of the Miocene Formation of the 

 U. S.,'pl. XLV., fig. II. 



" Conrad's type was stated by him to be 4 in. long. The specimens which 

 he gave to the Academy of Natural Sciences are still smaller. The speci- 

 men which I send to you is 7^ in. long; but one, of the same species, 9 

 in. long was found by Prof Heilpriil and myself in Florida in 1886. 



" Fig. 2 represents the same species with the shoulder angle slightly 

 developed, but it has no rudimentary spines. 



" In Fig. 3 the angle of the shoulder is a little more pronounced, and 

 rudimentary spines are visible. 



" In Fig. 4 the spines are still more developed on one side. 



" Fig. 5 represents the fossil Ftilgur perversus with spines not developed 

 to the proportions of the common living species. 



" Fig. 6 represents the typical fossil Fidgur perversus. 



" Fig. 7 is a fair sample of the Fiilgur perversus now living on the west 

 coast of Florida. A few specimens of this species when young have been 

 found nearly similar to the fossil Fig. 3. They are not common ; but they 

 indicate an occasional reversion towards the original ancestral form Fig. i, 

 which is now extinct, as well as Fig. 2. 



" More specimens are seen like Fig. 4, and still more like Fig. 5 ; but 

 they are not common. 



" I have other shells, from the same bed, which illustrate intermediate 

 characters between all the forms in the collection which I send to you. 



" In the same pliocene bed, while such great changes were progressing 

 with the Fulgurs, there were other species of shells which, at the time, indi- 

 cated great stability in character ; though they evince a considerable amount 

 of variability at the present time. I refer to the Strombus pugilis and the 

 Melongena corona. 



" More than one hundred specimens of fossils of the former have been 

 examined without finding any spines on them ; while, at the present time, 

 this species is found on the west coast in great abundance, with the spines 

 in all the different stages of development. It thus appears that the non- 

 spinose variety Strombus alatus was the original form of 6". pugilis. 



" Another shell, the Melongena coroiia, found in the same bed, manifests 

 great uniformity in structure ; while, at the present time, it is probably the 

 most variable shell living on the coast of Florida. The form found in the 

 fossil bed is considered by Prof Heilprin to be entitled to be classed as a 

 different species from its descendant, the living form ; and he has described 

 it as Melongeiia subcoronata. 



" We thus find, in the same bed, one genus that was widely variable in 

 character, which now manifests much greater stability in structure ; and also 

 two genera that were quite fixed or stable, that, at the present time, are very 

 inconstant. 



