Bibliographical Notices. 55 



passed into a fossil state. The figures that illustrate this well- printed 

 volume are 213 in number, and are very accurately drawn and en- 

 graved. The number of species described is 268, of which there are 

 of Cirripedes 12, Conchifera 92, Brachiopoda2, Gasteropoda 154. Of 

 these, 29 belong to the land, 42 to fresh water, and 197 are marine. 



Relative to their geographical distribution Dr. Gould remarks : — 

 " The land and freshwater univalves are all distributed over every part 

 of the territory, with the exceptions of Helix hortensis, which is as 

 yet confined to some parts of the sea-coast, and Helix tridentata, hir- 

 suta, and monodon, which are found only in the interior and western 

 portions. Of the freshwater mussels we find Unio complanatus, radia- 

 tus, and probably nasutus, in every region ; U. cariosus is only found 

 in the Connecticut and its tributaries, and in Plymouth ponds ; Ano- 

 don cataracta, and Alasm. arcuata and marginata are found every- 

 where in the interior, while Anodon implicata is perhaps entirely 

 limited, in this state, to ponds in Essex and Middlesex, and Anodon 

 undulata to Blackstone river and its branches. 



" The distribution of the marine shells is well worthy of notice as 

 a geological fact. Cape Cod, the right arm of the Commonwealth, 

 reaches out into the ocean some fifty or sixty miles. It is nowhere 

 many miles wide ; but this narrow point of land has hitherto proved 

 a barrier to the migrations of many species of Mollusca. Several 

 genera and numerous species, which are separated by the interven- 

 tion of only a few miles of land, are effectually prevented from in- 

 termingling by the Cape, and do not pass from one side to the other. 

 No specimen of Cochlodesma, Mont acuta, Cumingia, Corbula, Ianthina, 

 Tornatella, Vermetus, Columbella, Cerithium, Pyrula, or Ranella, has 

 as yet been found to the north of Cape Cod ; while Panopaa, Glycy- 

 meris, Terebratula, Cemoria, Trichotropis, Rostellaria, Cancellaria, 

 and probably Cyprina and Cardita, do not seem to have passed to the 

 south of it. Of the 197 marine species, 83 do not pass to the south 

 shore, and 50 are not found on the north shore, of the Cape. The 

 remaining 64 take a wider range, and are found on both sides. 

 Buzzard's bay and the south shore have as yet been very little ex- 

 plored ; and we may yet expect to find many species peculiar to 

 those localities. 



" At least seventy of our species are also found on the trans- 

 atlantic shores ; and more than twenty of these have been described 

 by different American conchologists as new species. About twenty 

 may be regarded as intermediate, being found most frequently by 

 fishermen about the banks, Newfoundland, and the islands inter- 

 vening between Greenland and England." — Page 315-316. 



Dr. Gould has too seldom noticed the animal of the shells he has 

 so well described; his account of the Mollusca Nudibrancfiia is 

 meagre, and the list scanty ; of the Cephalopoda, two species only 

 are catalogued ; and his catalogue of the Crustacea, Annelida, and 

 Radiata is useless, and needs to be worked anew. The Doctor is 

 well aware of the truth of this censure : — " The list," he says, 

 " serves to show that we have about us an abundance of animals 

 which have hitherto found few devotees in this country. So few 

 gleanings have been made in this field, that no other promises a more 



