302 PUOCKEDINGS OF THE JI ALACOLOGICAT, SOCIETY. 



It nuist be obvious that these names are vernaculars only, the Latin 

 name Fimbria of Megerle appearing solely because Megerle gave no 

 French equivalent. Such are continually repeated througliout, and 

 similar to the first named may be quoted " Les V. Mactroides ", 

 a section of Venus,]). 339, and "Les V. Lucinoides", another section 

 of Venus, p. 340. As of Blainville, then, either of the Diet. Sci. Nat. 

 or of the Manuel, P/iacoides ca\uiot be utilized. I next find Phacoides 

 under the following conditions: In the Proc. Zool. Soc. 1847, p. 195, 

 Gray Av rote — '■'■Lucina, Brug., 1792. Lam., 1801. Venus, sp. Gmel. 

 Phacoides, l^VxiwN., 1825. Ven. jamaicensis.'''' This takes us back to 

 Lucina, its introduction and type. 



The name first appears at the head of the plates in the Tabl. 

 Encycl. Method. (Vers.), vol. ii. On pi. 284 it is first seen, and this 

 appeared in 1797, as far as at present known, not 1792, as once 

 thought, and accepted by Gray. No names are given to the species of 

 shells figured. Lamarck in the Mem. Soc. Nat. Hist. Paris, 1799, 

 p. 84, introduced Lucina, and gave as sole example Venus edentula, L. 

 The recognition of the plate above noted, made thirty years afterward, 

 gave the species as Lucina pensylvanica, jamaicensis, and edentula (L.). 



Under such circumstances I conclude Lamarck's fixation of a type 

 must be regarded as final. I do not, however, so regard Lamarck's 

 citation of a species of a Linnean genus. In 1801 Lamarck utilized 

 other species as examples, and in the case of Lucina changed his 

 choice to jamaicensis. The 1801 book being commonly available and 

 the 1799 article scarce, it was natural that Gray should consider the 

 second choice typical. He was probably ignorant of the earlier 

 selection. 



Gray's action was unhesitatingly endorsed by H. & A. Adams 

 (Gen. Rec. Moll., vol, ii, p. 466, April, 1857), who cited Phacoides, 

 Blainville, as a synonym of Lucine, sensu lato, their example being 

 also L. jamaicensis. As a sub-genus they proposed Miltha, p. 468, 

 the only example being childreni, Gray. 



Fischer in the Mati. de Conch., pp. 1142-4, June, 1887, noted 

 the confusion, and for Lucina, Lamarck, 1801, nan 1799, proposed 

 Dentilucina, with only L. jamaicensis, Lamarck, citing L. edentula as 

 type of Lucina, Lamk., 1799. He does not mention Phacoides, 

 probably considering it only a vernacular name, as it undoubtedly 

 was. I liave not traced the usage of Phacoides earlier than Dall, so 

 that it would become an absolute synonym of De^itilucina, Fischer, 

 since Dall's type is the same as Fischer's. 



Dall associates under his genus Phacoides the sub-genus Miltha of 

 H. & A. Adams. If this subordination Avere accepted, then the 

 genus name to be used vice Phacoides, Dall, would be Miltha, 

 H. & A.Adams, and the sub-genus to be recognized for the typical 

 sub-genus of Phacoides, Dall, would be Dentilucina, Fischer. 



Criticisms of these conclusions are desired, so as to fix the name for 

 these Lucinoid molluscs, which is certainly not Phacoides, Blainville. 



Placenta, Retzius. 

 A reference by Dall to the Portland Museum Catalogue caused the 

 investigation of that work. I propose to give full details concerning 



