Annual Report.] 190 [May 1, 



Dr. Gould says, " a single species under four of the names 

 that Mr. Say applied to as many diiferent species." Dr. 

 Gould then points out how, by the use of the microscope, and 

 a careful study of their minuter details, the classification of 

 them might be improved. This paper was illustrated by 

 about thirty figures carefully drawn by himself, with the aid. 

 of the microscope. 



In 1841, he read before this Society a paper entitled " Re- 

 sults of an examination of the species of shells of Massa- 

 chusetts, and of their Geographical Distribution." This is 

 the more noteworthy since the geograpliical distribution of 

 animals had at that time attracted but little attention, and 

 none amongst us. Now it involves one of the most impor- 

 tant zoological problems. From his examination it appeared 

 that of the shells found within the borders of the State, 

 forty-two were of land or fresh water, and two hundred and 

 three of marine origin. While some of the marine species 

 are found on the transatlantic shores, he thought that all 

 the fresh water or land species were imported. Animals 

 found in territories widely separated by salt water, appear to 

 have been created distinct, and ever remain so, unless mingled 

 by design or accidental transfer. 



Dr. Gould also points out in this paper the influence of shore 

 outlines, and shows from a comparison of species, that Cape 

 Cod, which stretches out into the sea in a cmwed direction 

 some forty or fifty miles, forms to some species an impassable 

 barrier. Of two hundred and three species, eighty do not pass 

 to the south, and thirty have not been found to the north. In 

 the same paper he calls attention to the importance of the fact 

 that certain species appear and disappear suddenly, and of the 

 necessity, in order to construct a correct catalogue of the 

 shells of any region, to extend observations through a series 

 of years, a consideration which many naturalists, even of the 

 present day, might j^rofit by. In the spring of 1830, Osteo- 

 desrmis was strewed upon Chelsea Beach in great number, 

 and of very large size, but had never been observed there 

 before, and has scarcely been seen since. Cyprina Iceland- 

 ica, Solemya velutn^ Varenius gemma and Margarita arctica, 

 also present instances of periodicity at long intervals. Dur- 



