134 AMERICAN JOURNAL 



that a globose, capacious form should embrace a larger number 

 of young. 



It is true, however, generally, in any given species, that the 

 more capacious individual will be found most prolific of its spe- 

 cies. But aside from the variation in capacity in the individu- 

 als of a species, it is not true that variation in capacity among a 

 number of species is an indication of the relative number of 

 young that a species will produce. 



Percentage of reversed young. — With a few exceptions only, it 

 will be found that the species belonging to the subgenus 3Ielan- 

 tho produce a certain percentage of reversed young. My earlier 

 investigations, limited to the few species coming under my own 

 immediate observation, disclosed a singular uniformity in the 

 three species rufa, deeisa, Integra, — about two per cent, of the 

 young of these species being reversed. Later examinations of 

 these species seem to indicate a slight increase, at least for rufa 

 and integra. In other species the percentage varies from that of 

 those named. 



From what has been stated in the preceding remarks, it is 

 apparent that there are specific tests to be found in the embryo- 

 nic young of various species of Melantho. 



It remains now for these inferences to be confirmed or righted 

 by further systematic observations. 



Some of the particulars observed in my investigations may be 

 of interest, and serve as a reference for investigators favorably 

 situated for examining species that are not immediately accessible 

 to me. Those which seem worthy of note are here presented. 



A large specimen of M. pond'erosa, Say, from Murray county, 

 Ga., sent by Mr. Downie to Mr. Lea (and from him to me), con- 

 tained 102 young. These were smaller than I have observed in 

 smaller species that have come under my observation, 



A similar, but slightly smaller shell in alcohol, taken from the 

 Coosa River, Ala., by Dr. Showalter, contained a much smaller 

 number of specimens, — namely, 22. In these two adults the 

 young were of corresponding small size, and rather more globose 

 (or less acute) than the young of integra. No reversed specimens 

 were observed in the young of either specimen. 



Of nine specimens of a species from the Ohio Canal, Columbus, 

 Ohio (communicated to me, with two other species, by Mr. Henry 

 Moores), to which species, for convenience of reference, I gave 

 the name obesa several years ago, the aggregate number of young 

 was 276, of which 11 were reversed ; the average of young to 

 each adult being 31 ; the percentage of reversed young being 

 about 4 per cent. The fewest young in any one specimen was 

 10 ; reversed young 0. The largest number of young in any one 



