148 MOLLUSCA FROM THE CRAG. 



It has been justly remarked, by ^lessrs. Forbes and Hanley, that in consequence 

 of its anomalous character, this shell has been bandied about and placed in many 

 different genera, but generally with a doubt respecting its true position ; the deep 

 palleal sinus indicated the possession of somewhat elongated or at least projecting 

 siphons, thereby differing from the animals of true Litcina, in which genus some 

 authors had placed it, where from its dental characters and general appearance it 

 seemed most entitled to be situated. They have, however, removed it from among the 

 family LacinidcB, and placed it in the Vencridtc, in consequence of the deeply sinuated 

 form of the palleal impression ; and this view of its connection seems to have been 

 taken by other Malacologists. 



The possession of a sinus in the impression of the mantle mark is a distinction, 

 wc have elsewhere seen, in all j)robability sufficient for the removal of a shell with 

 such a character out of a genus, where others have the mantle mark perfectly entire, 

 but there is no sufficient reason in that alone that it should be removed to any very 

 distant position. Its general affinities appear more in connection with those of Lucina 

 than wuth those of Venus, differing from the former only in the aberrant character of a 

 prolongation in the siphonal tubes, bearing the same relationship to Lucina, or rather 

 to Diphdonta, that Leda docs to Nucula, or as Adacna to Cardium : I have, therefore, again 

 ventured to remove it from among the VcneridcE to wliat appears a more correct position. 



The name of Mijmi was proposed in MS. for a genus by Dr. Leach, in which the 

 Vp.nm undata, Penn., was placed; and this name has been published by Lamarck in his 

 ' Hist. Nat. des An. sans Vert.,' t. v, p. 543, 1818, thereby giving it a status in regard 

 to time ; and considering that sufficient for its right to priority, it was adopted by 

 myself in ' The Catal. of Crag Shells,' for the Crag species, but another well-identified 

 shell belonging to the genus Diphdonta had also attached to it the same generic 

 name, and this was puljlishcd by Brown, in 1827. It is not now possible to say which 

 of the two species was intended as the type of his proposed new genus, and therefore, 

 to unravel the difficulty, or rather to cut the Gordian knot, the authors of Lucinopsis 

 have, perhaps wisely, rejected in toto the name of Mi/sia. 



This appears a very natural genus, although very few species are yet known 

 either in a recent or fossil state. Two or three shells from the Grccnsand Formation, 

 figured and described under the name of Thetis, somewhat resemble it in the dental 

 characters, but they have a deeper and more angulated sinus in the mantle mark. 



1. Lucinopsis Lajonkairii, Pai/raudcau. Tab. XI, fig. 14, a — c. 



Ency. Method., pi. 272. fig. 2, a—b, 1800. 

 Veneri'pis Lajonkairii. Payr. Cat. JIoll.de I'lle de Corse, p. 3G, pi. 1, figs. 12, 13,1826. 



— — Desk. 2d cd. Lam., t. vi, p. 161, 1835. 



Venus lufinoides. Nyst. Rcch. Coq. Foss. Prov. d'Anv., pi. 11, No. 41, pi. 3, fig. 14. 

 Mysia ornata. S. Wood. Catalogue, 1840. 



Tellina LUPiNoiDEs. Xijst. Coq. Foss. de Bi-lg., p. Ill, pi. a, fig. 4, a — c, 1844. 

 — ? ARTICULATA. Id. - - - J). 110, pi. 6, fig. 1, a, b. 



