41 



Dosinia exoleta Linne. PI. VI, f. 22. 



(^yst. nat. od. XII, p. 434, ;is Vemiü exolet;^.— Chemnitz, Cotich. Cab. vol. 

 G, p. 4.S, pi. ;58, f. 104, ilo.-Gim;liu,S.yst. n:vt. Linn. cJ. XIII, p. 32S4, do.- 

 Moutiigne, test, lirit. p. 116, do. — Lamarck, hist. nat. pp. vol. 5, p. 512, 

 and id. second, cd. by Dcshayes, vol. 6, p. 314, jus Cytheica.— rhilippi. 

 Eiiuin. ^loll. feie. vol. 2, p. 32, and abbild. I, ]). l7l, do. — Keevc, Concli. 

 Ic. Artemis, pi. 5, f. 29 — Forbes and Hanley, Brit. Moll. vol. 1, p. 428, 

 pi. 23, f. 3, 4.— Sowerby, Thes. Conch, p. COS, pi. 1 & 1, f. 12-14.-Jef- 

 freys, brit. Conch, vol. II, p. 327, as Venus.— Weinkauff, Conch, d. TMit- 

 telm. vol. 1. p. 120.— Guldfiiss. Totref. German, vol. 2, p. 241, pi. 14'J. 

 f. 18, as Cytherea.— Hoeriies, Foss. JIoll. des Wiener Beckens, vol. 2, p. 

 143, f. 16, f. 2,— Syn. D. lentiforinis (Venns) Sowerb}-, Min. Conch. ]il. 

 203 and Wood, Crag Moll. II, p. 215, pi. 20, f. 7. Syn. also D. Japonica 

 Reeve, Conch. Icon. Artemis, ]il. 3, f. 17, Sowerby Thes. vul. 2, p. Gßl), 

 pi. 143, f. 60, Eoemer, Dosiuia, p.' 60, pi. 11, f. 4, Lischke, -Japan. 

 Meeres-Conch. v. 1 , p. 127, v. 3, p. 58, and Morse. Shell-monnd of Omori, 

 p. 28, pi. 18, f. 7. Syn. also Dosiuia 'J'roschdi Lischke, -Japan. Jlceres- 

 Couch. III. p. SO, pi. 8, f. 1-3). 



The most minute details of the hinge being exactly the same, tliere can br 

 no doidifc about tb<; Oosiniie, which I got from Ojl in an unexpectedly rich s«ipply 

 and which were indeed the most common shells of this locality, lielonging to the 

 same SjK'cies as Dosinia exoleta L., from which also D. lentiformis was quite un- 

 ncces,sarily separated. Outline and area, as well as pallia] sinus, e.vbibit, in the 

 Oii-s|K'cimens, all the variations indicated under all the above cpioted names 

 and by any of the mentioned authors. Especially the character of the stionger 

 demarcation of the area, stippo.sed to l« typical for P. Trosiheli, ])assi's so gra- 

 dually into the common form, and is not atal! constantly connected with any shajye 

 of the pallial sinus or of the ontline, or even of the ct>lonng, that in fact — as I 

 convinced myself in examining the Tokio collections — a great many of (he .Ja|ia- 

 nesc 8{x;ciinens could not be strictly assigned to either of the forms. 



Indeed the shell varies much, and as the large lunnbcr of s])eciincns from 

 one locality and formation, viz. Oji, demonstnites, this variability can not be ex- 

 I)lained as a st-ixge of evolution, or as a local modilication. We must accept it 

 as a property of the specii^, wliieh, on the rither hand, peems to l)e well distin- 

 guished from the s|iecic8 of the same geiuiK, e. g. D. lineta I'ulteney, c!o;-e as 

 thi.s fonn is allieil, or 1). (Artemis) landiata Gould in Otia Conch, p. 84 and 

 AtliUi of Wilkes Exp. pi. 37, f. 536. Dosinia e.xoleta L. then-fom nmst l>e con- 

 siilered as on(f of the truly pala'arctie ftirms of which indeed already a certain 

 nundH-r has Inn-n gener.illy admitted. We may adil that thi' range of the 

 variations is not essentially increased by all the other .Ia|i;uii'.«c loralities, fossil 

 or recent. 



Considering these variation.", we must indeed reject tlio conclusions of M<)r.se, 



