1825.} not taken Notice of hy Lamarck. 139 



Modiola castanea. Testa convexa, subcylindiica, castauea 

 pellucida, concentrice striata, List, t. 1065, f. 9, Rumph. t. 46, 



f. 2. . ^, 



Mod. Brasiliensis. Mytilus modiolus Brasihensis, Uiemii. xi. 



f. 2018, 2019. Mytilus latus jun, Dilhv. ! 



Mytilus dilatatm. Testa trigona postice rotundata, cotn- 

 pressa, umbonibus acutis incurvatibus— Mediterranean. 



Mytl Volge/isis. Mytilusy fluvisK, Volga C7/cw«. Myt. poly- *y 

 morphus, Gmelin, perhaps will form a genus distinct from / 

 Mytilus, and peculiar for its freshwater habitation ; and like 

 shells of that station, the animal can live for a long time out of 

 water. I have kept one for three weeks, when it was still 

 healthy. It is found in the Commercial Docks, where it most 

 likely "has been introduced with timber from the Volga. 



Crenatula. This genus may be divided into two sections, 

 which may perhaps hereafter be considered as genera by the 

 same character as separates Mj/fihis from Modiola, % 1. Testa 

 quadrata nmbojiitms anterioribus, which includes the species or 

 rather varieties mentioned by Lamarck. § 2. Testa ovata umbo- 

 nibus sub anterioribus (Dalacia) containing the foUownig : 



Cre. folium. Testa "albida radiata compressa ; latere antico 

 rotundato, postico alata, Brande's Journal, xv. t.2, f. 81. figura 

 pulcherrima. Vulsella folium, Humph. Mus Cracherode. 



Lima gigantea. Testa crasoa^ ponderosa, subauriculata albi- 

 do-rosea, irregulariter radiata costata striata; intus alba, rufo 

 maculata. lat. 15-4, long. 18-4, unc. 



Lim.excavata. Ostrea excavata, G^ne//^. 

 OsTREA prismatica. Testa elongata lamellosa; intus vio- 

 lacea, albido macerata iridescens ; impressione muscularis reni- 

 formi translucente ; umbonibus truncatis ; valva supenoris 

 planulata. long. 2, lat. 6, unc. 



Anomia 1-osea. Tellina aenigmatica, Chemn. x. t. 199, i. 

 1949, 1950. Mus. Tankerville. 



DisciNA. This genus is certainly distinct ivomOrbicula, 

 which appears to be the same as Crania. 

 Dis. l&vis. Orbicula ! Isevis, Sow. 



2. MoLi.uscA Pteropoda. 

 Lamarck, Cuvier, and Peron, appear to have reversed these 

 animals and the heteropes, and called their belly their back, for 

 they certainly, like the gasteropodes, swim with their belly- 

 upwards, and consequently the latter have their shell placed on 

 their mantle as in the gasteropodes ; to this order should be 

 referred the genus J ant hi na. 



3. MoLLuscA Gasteropoda. 

 Pleurobranchus Moutagui. Bulla Plumula, Montague. 

 Pleu, argenteus. BuU^ membranacea, Montague. 



