208 Prof. A. E. Verril] on the MoUusca 



But the special errors to which I wish to call attention occur 

 in the table of species, showing their geographical distribution. 

 These relate both to the names and specific identity of certain 

 shells, and to the geographical distribution. Although not 

 agreeing with the author in regard to many of his remarks con- 

 cerning the generic relations and names of species, I do not 

 propose to discuss them here ; for there seems to be no danger 

 of their general adoption either in Europe or America. 



The following marine species (named as in Gould) which 

 Mr. Jeffreys puts down as belonging to the region north of 

 Cape Cod, actually belong properly to the region south of 

 Cape Cod, extending in most cases to the Carolina coasts or 

 beyond, while north of Cape Cod they are rare or local, viz.: — 

 Cochlodesma Leanum^ Mactra lateralis, Petricola pholadiformis, 

 P. dactyluSj Oouldia mactracea, Cytherea convexa, Venus 

 mercenaria, V. notata, Gemma cjemma, Liocardium Mortoni, 

 Area transversa, Modiola iilicatula, Pecten irradians, Ostrea 

 virgimana, Anomia electrica (not of Linn.), Diapliana debilis, 

 Cylichna oryza, Placobranchus catulus, Crepidula fornicata, 

 C. plana, C. convexa, C. glaiica, lanthina fragilis, Bittium 

 Greenii, Odostomia hisuturalis, 0. seminuda, TurhoniUa in- 

 terrupta, Pleiirotoma hicarinata, P. plicata, Nassa ohsoleta, 

 Buccinum cinereum, Diacria trispinosa, Loligo Pealii. 



The following, to which a northern distribution is likewise 

 given, are also found far south of Cape Cod, and many of them 

 belong quite as much to the southern as to the northern division ; 

 and some of them are decidedly southern, extending even to the 

 Gulf of Mexico -.— Teredo navalis, T. megotara, T. chlorotica, 

 Solen ensis, MachcBra costata, Pandora trilineata, Lyonsia 

 hyalina, Mactra solidissima, KelUa planulata, Macoma fusca, 

 Tellina tenera, Astarte castanea, A. quadrans, A. sulcata, 

 Nucula proxima, Yoldia Umatula, Mytilus edulis, Elysia chlo- 

 rotica, Crucibulum striatum, Littorina rudis, L. tenebrosa, 

 L. palliata, Liinatia heros, L. triseriata, Nassa trivittata, 

 Melampushidentatus, Alexia myosotis. 



Many others, not named in the above lists, are not limited 

 by Cape Cod ; but as they belong properly to the northern 

 division, they are here omitted. 



As an offset to these numerous instances in Avhich he has 

 unduly exaggerated our northern fauna, we find not one un- 

 doubted instance of an error on the other side, among the 

 marine shells. 



The distribution indicated for our land and freshwater shells 

 is even more erroneous. It is sufficiently evident that Cape 

 Cod is in no sense a proper boundary between the northern and 

 southern fluviatile and terrestrial species ; but, disregarding 



