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761 



TKKTIARY FAUNA OF FLORIDA 



and less spiny than on the other. The spinosity varies greatly ; some indi- 

 viduals have almost none, others are profusely spiny, and others, again, have 

 the spines limited almost entirely to the major ribs, which vary greatly in 

 number. There is occasionally a distinct ctenolium in adult specimens. The 

 colors and their distribution vary as in many Pectens. 



I have seen from the West Indian region but one species of large folia- 

 ceous Spondylus (with one well-marked variety), the present species. There 

 is one deep-water species, common to the Mediterranean, the Spondyhis 

 Gitssniii of Costa, which is small, with acicular spines, and colorless. 



The Eocene -S". aimissiopse de Gregorio is the young of Plicatnla fila- 

 mcntosa Conrad. S. iiiomalits Whitfield, from the Miocene of New Jersey, 

 is based on a smooth specimen of Plicatnla dcnsata Conrad. S. cstrallcnsis 

 Conrad, 1857, afterwards altered to .V. cstrcllaiins, from the Miocene of the 

 Kstrella valley, California, was based on a much-mutilated specimen of Lyro- 

 pcctcn. The very imperfect type of Pcctcn anisoplcitra Conrad from North 

 Carolina strongly resembles a Spondyhts, but is too incomplete to permit of 

 positive determination. A species doubtfully referred to this genus is men- 

 tioned by Ileilprin in his paper on the Eocene Mollusca of Texas (1'roc. 

 Acad. Nat. Sci. Phila. for 1890, p. 404). 



Professor Harris has figured a valve of a Spondylus from the Chickasawan 

 or Lignitic beds of Hatchetigbee Bluff, which he doubtfully refers as a variety 

 to S. (luinosits Morton. The specimen is too imperfect to afford definite 

 evidence, but may probably turn out to be a distinct species (cf. Bull Pal., 

 No. 9, p. 42, pi. 6, fig. 11, 1897). 



Genus PLICATULA Lamarck. 

 riicatitln Lain., Syst. An. s. Vert., p. 132, 1801. Type P. ^ibbo^i Lain., /. f. == P. raiiwsa 



Lam., 1819. 

 //,ir/>,i.\- Parkinson, Orjj. Rem., 3, pi. 12, 1811 ; Brookes, Intr. Condi., p. 83, 1815. Type 



//. 1'tii-kiiisiniii Bron 11. 



<^//Yiu>iiii,i Conrad, 1'roc. Acad. Nat. Sci. Phila. for 1872, p. 216. Type O. cii>v/in<-itsis 

 Conr. 



The only established species mentioned by Lamarck in the Systeme, 

 wlicrc he described the genus, is the West Indian form, which he at first 

 named P. g'ibbosa and wrongly identified with the Chinese Spoiidv/ns plicatits of 

 Linne. In 1819 he arbitrarily changed the name to rainosa. Linne's still 

 preserved type specimen and designated habitat show that his species was not 



