FREE INSTITUTE OF SCIENCE 



795 

 TERTIARY FAUNA OF FLORIDA 



Mytiliis plicaluhis Sby., Genera, Myt., pi. vii., 1822 ; Deshayes, Enc. Meth., ii., p. 568, 



pi. 220, fig. 5, 1830; Stimpson, Sh. N. Engl., p. 12, 1851. 

 Modiola semicostata Conr., Journ. Acad. Nat. Sci. Phila., vii., p. 244, pi. 20, fig. 7, 1837. 



(Not of Ball, Bull. 37, 1889.) 

 Modiola semicosia Verrill (as of Conrad), Inv. An. Vineyard Sound, p. 693, 1873. 

 {?)Mytilus clava Meuschen, Mus. Gronov., 1778 {Jide Morch, Cat. Yoldi, ii., p. 54, 1S53). 

 {f)Mytilus viagcUanus Meuschen, Mus. Gevers, 1787 (^fidc Morch, op. cit., p. 54, 1853). 

 Brachydontcs clava Morch, Cat. Yoldi, ii., p. 54, 1853. 

 Periia {Brachydontes) plicatula H. and A. Adams, ii., p. 517, 1857. 

 Modiola demissa Conrad, Am. Journ. Sci., 2d Ser., ii., p. 44, 1846. 



Pliocene marls of the Caloosahatchie River, Florida, rare, Dall ; Post 

 Pliocene of Massachusetts Bay ; recent from Nova Scotia to Georgia, west 

 Florida, and Texas ; locally restricted towards the extremes of its distribution. 

 There is no doubt of the applicability of Dillwyn's name to our common 

 plicate mussel. The two names of Meuschen are doubtful, and probably 

 cover a confusion of our species with the Mytilus iiiagcUaniciis of authors. I 

 have not been able to consult Meuschen's works, but believe the names are 

 not accompanied by any description or figure, and are identified chiefly by 

 means of the alleged localities. At all events, until the information is fuller 

 and more satisfactory, it seems inadvisable to use Meuschen's earlier name, 

 while his later one is inapplicable. There are two distinguishable geographical 

 races of this species, the form found north of New York, and figured in the 

 Encyclopedic Methodique, which Lamarck called plicatuhis and Conrad scmi- 

 costatus ; and the southern form, which is more attenuated behind, has a more 

 delicate and elegant sculpture, the ribs being minutely granulose, and the 

 color lighter and of a less intense purple. Dillwyn's name included both, 

 and may be specially centred on the southern form, while that of Massachu- 

 setts Bay may be regarded as forming a variety plicatuhis. In my Bulletin 

 37, United States National Museum, the two names were accidentally trans- 

 posed. 



Modiolus (Brachydontes) citrinus Bolten. 

 A}'ca modiolus Linne, Syst. Nat., Ed. xii., p. 1141, 1767. 

 My/ilus citrinus polydcntatus, etc., Chemn., Conch. Cab., viii., p. 175, pi. 84, fig. 754, 



1785. 

 Mytiliis flavicans (Sol. MS.) Humphrey, Mus. Calon., p. 43, 1797 (no description or 



figure). 

 Mytilus citrinus ^o\X.e.r\, Mus. Bolt., p. 157, 1798; Ed. ii., p. iii. No. 45, 1819. 

 Mytilus exustus Gmelin, Syst. Nat., vi., p. 3352, 1792 ; not of Linne. 



