of Europe and North America. 209 



this, there are no reasons whatever for most of the special in- 

 dications that he gives. 



Thus he gives the northern distribution to all of the sixteen 

 species of Sphcerium and Pisi'dium ; but most of them are well 

 known to be widely distributed over the eastern, middle, and 

 western parts of the United States, some even extending to the 

 southern parts. Um'o complanatus, U. nasutus^ Margaritana 

 arcuata, and Anodon impUcatus are indicated as distributed 

 north of Cape Cod ; but all these are found over most of the 

 northern and middle states and some in the western, while the 

 last one is somewhat rare at the north. But Unio radiatus, 

 U. carwsus, U. ochraceus, Margaritana undulata^ M. mar- 

 ginata, Anodon fluviat His , and A. undulatus are put down as 

 southern. It would certainly be difficult to show that these, 

 as a group, are more southern than the previous lot ; for most 

 of them have nearly the same wide distribution, and all of them, 

 except U. cariosKs, occur even in Maine. Some of them (as 

 U. radiatus, M. undulata, and A. Jiuviatilis) are the most 

 abundant species in all the waters of northern New England 

 and New Brunswick. The distribution given for the species 

 of Valvata, Melantho, and Amnicola is equally faulty. 



All of the eighty-one species of Helix, Hyalina, Macrocyclis, 

 Limax,Pupa, Vertigo, Succinea, Arion, Zonites, Tebennophorus, 

 Limncea, Physa, Bulinus, Planorhis, and Ajicylus are set down 

 as having the northern distribution, except Hyalina Binneyana^ 

 Pupa fallax, Limncea catascopium, and Physa ancillaria. 

 But every American conchologist knows that nearly all of 

 those species are very widely distributed over North America, 

 east, west, north, and south, many of them being limited only 

 by the Gulf of Mexico on the south and California or the 

 Pacific on the west. Nor is there any reason for the distinction 

 made in the case of the four species named above ; for these, 

 though differing among themselves, have the same distribution 

 as many of those put down as northern, while H. Binneyana 

 and P. ancillaria certainly have a very northern range, for 

 they are abmidant in Maine, New Brunswick, and Canada. 



It is evident that such numerous errors of this kind render 

 the paper, so far as geographical distribution is concerned, 

 quite worthless ; for it is sure to mislead. 



Most of these errors might have been easily avoided had the 

 author depended less on Gould's Avork and more on the recent 

 works of American conchologists ; for there is no lack of data 

 in regard to the distribution of most of our shells. Even Dr. 

 Stimpson's 'Shells of New I^ngland' (1S51), if consulted, 

 might have saved most of the errors in regard to the distribution 

 of the marine shells. 



Ann. & Mag. N. Hist. Scr. 4. Vol. xi. 14 



