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TERTIARY FAUNA OF FLORIDA 



(Mus. Boltenianum, p. 166, 1798), while in 1799 Lamarck (Prodrome, p. 82) 

 adopted Solander's name with the original type. In 1817 Schumacher used 

 Retzius's name and correctly placed Placnna in its synonymy. Since that 

 time, however, as was natural, the name adopted by Lamarck has had the 

 wider currency, perhaps partly on account of the erroneous statement by 

 Herrmannsen (Ind. Gen. Mai., ii., p. 277) that Chemnitz refers to Solander's 

 manuscript name in the volume of the Conchylicn Cabinet published in 1785, 

 three years before Retzius gave Da Costa's name a binomial standing. A 

 careful search of Chemnitz in the place indicated shows no reference what- 

 ever to Solander or his name, as has already been pointed out by Deshayes. 

 In 1848 Gray enumerated the species of Placenta Retz. (P. Z. S., 1848, p. 

 114) and divided the genus into two sections or subgenera, I, Placentas, s., 

 typified by P. placenta Lin., and 2, Ephippiuin (Chemn.), after Bolten (+ Scl- 

 laria Link, 1807), comprising the saddle-oysters. The name Epliippiiun 

 (Hulten) antedates by four years its use in Entomology, even if we do not 

 go back to the non-binomial Chemnitz, and though part of the species were 

 referable to Placenta Retz., the remainder, belonging to an unnamed group, 

 were entitled to retain Bolten's name. If Bolten's name had been entirely 

 new the absence of a diagnosis might militate against its acceptance, but as 

 it is really a revival of a well-known but not binomially established name, 

 with proper references to Chemnitz's and other figures and to Gmelin's syn- 

 onymes, while there can be no possible doubt as to the species included, it 

 would seem that no question need arise on this account. 



In 1864 Deshayes referred a problematical fossil (Placuna solida Desh.) 

 to this group under the name of Hemiplicatula, for which in 1886 Fischer 

 proposed the emended form of Sciniplicatitla. Its true relations can only be 

 determined by a more critical examination than it seems yet to have received. 



In 1867 Conrad described a genus Paranoinia, from the Ripley group 

 (Upper Cretaceous) of Alabama, to which he referred his Placunanomia 

 Saffordi (Journ. Acad. Nat. Sci , 2d Ser., iv., p. 290, pi. 46, fig. 2l)and the 

 Placmia scahra of Morton. The typical species is ill preserved, and the beaks 

 almost always wanting, but, from the examination of a large number of speci- 

 mens, it seems probable that the genus resembles Mania in its external char- 

 acters ; the presence of a triangular chondrophore recalls Anoinia, but there 

 is not sufficient evidence of a permanent foramen, the muscular impressions 

 are not preserved, and there is in the right valve, associated with the single 

 chondrophore, a pair of low, narrow crests, recalling those of Placenta, but 



