Morse.] 318 [February 17, 



Dr. B. Joy Jeffries stated that the experiments with after 

 images reported by the President at a previous meeting, 

 and a further continuation of them by himself subsequently, 

 although original with both observers, were nevertheless cov- 

 ered by others published by Prof Volkmann in 1863. By his 

 very ingenious series of experimentations Volkmann had been 

 able to deduce certain laws in reference to the projection of 

 after images, which laws the experiments reported at this 

 Society confirmed. Dr. Jeffries thought the result of his own 

 experience carried the subject even a step further than Volk- 

 mann had done, giving as it did still greater part to the mind 

 in governing the projection of after images. By means of 

 models and diagrams Dr. Jeffries illustrated Volkmann's ex- 

 periments and gave the results deduced from them which he 

 showed were the same as those arrived at by the President's 

 and his own experiments. 



Mr. Edwai'd S. Morse called attention to a recent state- 

 ment in the Zoological Record concerning a series of articles 

 by himself on the Land Snails of New England, in which 

 the reviewer remarked that he had returned to the system of 

 Lamarck and Pfeiffer in the classification of these animals. 



The articles in question, being published in a popular magazine 

 •were necessarily rendered as simple as possible, and divested of all 

 technical details, and on this account only the earlier nomenclature 

 was used. Mr. Morse disclaimed the intention of abandoning the 

 position he had previously^ maintained, that these animals were divisi- 

 ble into natural groups by the structural peculiarities of the principal 

 pai-ts of the animal, such as the character of the lingual membrane, 

 the form of the buccal plate, etc. 



While in general he had followed Albers in these subdivisions, he 

 felt that he could not have adopted all of his genera without open 

 violation to the natural characters of the animal, and though strongly 

 tempted to follow the example of other systematists and include 

 extra limital species in the new genera proposed, had i-efrained from 

 doing so since he had had no opportunity at that time of examining 



1 Observations on the Terrestrial Pulmoiiifera of Maine, etc., 1864. 



