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761 

 TERTIARY 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 Spondylns (with one well-marked variety), — the present species. There 

 is one deep-water species, common to the Mediterranean, — -the Spondylus 

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



The Eocene 5. aiiinssiopse de Gregorio is the young of Flicatida fila- 

 mentosa Conrad. 5. inornaUts Whitfield, from the Miocene of New Jersey, 

 is based on a smooth specimen of Piicatnla dcnsata Conrad. 5. estrallciisis 

 Conrad, 1S57, afterwards altered to S. cstrcllaiiiis, from the Miocene of the 

 Estrella valley, California, was based on a much-mutilated specimen of Lyi-o- 

 pcctcu. The very imperfect type of Pcctcn anisoplcura Conrad from North 

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

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

 tioned by Heilprin in his paper on the Eocene Mollusca of Texas (Proc. 

 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 5. duuiosus 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. II, 1897). 



Genus PLICATULA Lamarck. 

 Plicatida Lam., Syst. An. s. Vert., p. 132, 1801. Type P. gibbosa Lam., l. c. = P. rainosa 



Lam., 1S19. 

 Harpa.x Parkinson, Org. Rem., 3, pi. 12, iSii ; Brookes, Litr. Conch., p. 83, 1815. Type 



H. Parkinsonii Bronn. 

 Ostrcnomia Conrad, Proc. Acad. Nat. Sci. Phila. for 1872, p. 216. Type O. carolinensis 

 Conr. 



The only established species mentioned by Lamarck in the Systeme, 

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

 named P. gibbosa and wrongly identified with the Chinese Spondylus plicatus of 

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

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



