358. TRANSACTIONS OF THE WAGNER FREE 



Crepidula plana Say. 



C. plana Say, Journ. Acad. Nat. Sci. Phila. ii. p. 226, 1822 ; Tuomey and Holmes, Pleioc. 



Fos. S. C, p. Ill, pi. 25, fig. 12, 1857 ; Emmons, Geol. N. C, p. 276, fig. 195, 1858. 

 C. unguiformis Lamarck, of many authorities. 

 C. protea Orbigny, Moll. Cuba, ii. p. 192, pi. xxiv. figs. 30-33, 1S42 ; Dall, Blake Gastr., p. 



285, 1889. 

 C. lamina H. C. Lea, Trans. Am'. Phil. Soc, 2d Ser. ix. p. 250, pi. 35, fig. 42, 1845. 



Fossil in the Older Miocene of the Chipola beds, Burns, and of the An- 

 tilles, Gabb, Guppy, etc. ; in the Chesapeake Miocene throughout; in the 

 Pliocene of the Caloosahatchie and Myakka River, Fla.,"VVillcox ; in the Post- 

 Pliocene of North Creek, Fla., Simmons's Bluff, S. C, and Sankoty Head, 

 Mass. ; and living along the whole coast, from Prince Edward's Island south- 

 ward in the cavity of dead shells and rarely on their exterior. 



Having much confidence that this form will prove to be a dynamic muta- 

 tion of other resident species, both in the fossil and the recent faunas, I prefer 

 to adopt a name for it which applies strictly to the American form, though 

 the latter cannot be distinguished by the shell from the European itngiufoi'nns 

 and analogous individuals found in foreign waters in most parts of the world. 

 The fossils are absolutely identical in all essential characters with the recent 

 specimens. 



Beside the species above mentioned, there are two forms from the Cali- 

 fornia and Oregon Miocene which should probably be united, the C. princeps 

 and C. prampta Conrad, the latter name having priority. Both have been 

 united with C. grandis Middendorf, but after studying a large number of this 

 recent species I cannot agree with this view of the matter. The C. prcerupta 

 is much more like C. ponderosa Lea than the recent shell. It occurs also 

 very abundantly in the Miocene of Alaska at the northern shore of Unga and 

 Popoff Islands, Shumagins, and in the Pliocene of California. C. rostralis 

 Conr., from the Astoria Miocene, is probably identical with C. adnnca Sby., 

 which is found in the Pliocene and recent faunas of California. C. dorsata 

 Brod. is also reported from the California Pliocene. Gabb has proposed for 

 a small, obliquely twisted Crepidula of the California Eocene the subgeneric 

 name of Spirocrypta, but with our present knowledge this subdivision seems 

 hardly needed ; his type is C. pileinn Gabb, from the Tejon group. 



Family CAPULID/E. 



The species of this family are curiously absent from the shallow waters 

 of the coast and from the Tertiary beds. Capidus americamis Conrad belongs 

 in the next family, and should be referred to the genus Amalthea. The pecu- 

 liar irregularities of its aperture show that it was a commensal or semiparasitic 

 species, probably on some echinoid. It is from the Eocene of Jackson, Miss. 

 The Capidus Bullii of Meek's Checklist of Miocene Fossils is the cup of a 

 Crucibtdujii, described as an Hipponyx by Tuomey and Holmes, and referred 



