MOLLUSCA COXCIUFERA. 227 



far as to consider the position as oblique, with the anus 

 directed upwards and backwards, Blainville's representation, 

 which makes the hinge superior, should be preferred. 

 With respect to the asymmetrical Conchifers, the author very 

 acutely observes, that they stand in the same relation to- 

 wards the symmetrical as the Pleuronectce do to the rest of 

 the fishes, and that, consequently, in them the valves are to 

 be distinguished not into left and right, but into superior 

 and inferior. They are placed on the side. (Comptes 

 rendus, xvi, p. 561, 1843; Froriep's Notiz. xxvii, p. 193.) 

 This innovation of D'Orbignv's is attacked by Deshaves 



o / */ / 



(Comptes reudus, xvii, p. 1333), and defended again by 

 D'Orbigny. (Ib. p. 1364.) 



Templetou states that Acicula radiata, Leach, is the Pearl-oyster of 

 Ceylou. It is figured, 'Annals' xi, p. 325, pi. 1 . 



Menke describes (1. c.) a new Plicatula, P. imbricata, with scaled pli- 

 cations. 



Lima Cumingil and angulata, Sower. (Proc. p. 23), both figured in his 

 ' Thesaurus.' 



Pecten bifidus, Menke, the costaj of the convex valve divided by a 

 groove. 



Two new species of Pinna are instituted by Meuke (1. c.), P. mrgata and 

 deltodes ; the latter from the mouth of Victoria River. 



Kiister contends (Isis, 1843, p. 565) for the dangerous 

 assertion that in Europe numerous species of Unio and 

 Anodonta should be distinguished. It is very possible that 

 an accurate study and careful discrimination would be of 

 great utility, but the numerous European species adduced 

 can only be regarded, in my opinion, as local varieties of a 

 few species. This is not the place to carry out this view 

 further, and it is here merely referred to. 



Unio bigerrensis (Guerin, Mag. pi. 64), testa pseudo-elliptica, crassa, non 

 hiante, posterius bicolorata, oblique truncata ; radiis viridibus aut-rufescen- 

 tibus divergentibus : natibus decorticatis erosissimis ; dentibus cardinalibus 

 brevibus crassis, sulcatis, et dentatis nou regulatim, laterali acuto lamelloso. 

 U. manca id. (ib.), testa oblouga reni-formis, uatibus prominulis, non decor- 

 ticatis, undato-rugosis. Both from Trance. U. panacoensis, v. d. Buscli in 

 Philippi (Heft 2), is a beautiful large species from the river Panaco, near 

 Tampico. 



