16 THE NAUTILUS. 



parts of Culm, though richer probably than is Porto Rico. The 

 distribution of its shells is far more general than as recorded in 

 Crosse's list, and the affinities between the faunas of North Haiti 

 and Cuba and South Haiti and Jamaica are not so decidedly marked 

 as heretofore supposed. 



The presence of a large number of the Thaumasia group of Uro- 

 coptida? in the Southern peninsula is significant, yet we encountered 

 Lucidella, Stoastoma and a probable Sagda in the north. 



ALASMIDONTA MARGINATA SAY. 



In the April number of the Nautilus Professor Chailes Le Roy 

 Wheeler calls attention to the above species and is in doubt whether 

 this name should be applied to the somewhat solid, inflated, rhom- 

 boid western shell, or the less inflated, thinner, triangular form 

 from the Atlantic drainage. I am glad Professor Wheeler has 

 called attention to this, because at the time I made up the account 

 of Say's species for the Synopsis I overlooked the fact that it had 

 just been published in the Journal of the Academy of Natural 

 Sciences. In Dr. DalPs copy of the paper on Conchology by Say 

 in the third edition of Nicholson's Encyclopedia, Say says: "Found 

 in the river — " leaving it to lie understood that he was not certain 

 where it was found. Immediately after the dash there is written in 

 ink " Delaware." 



The description is not very clear, but I was inclined to believe 

 that it applied better to t lie eastern than the western form. Say 

 says that his shell is transversely oblong-suboval, and this outline 

 applies best to the eastern shell, which is often irregularly obovate, 

 while the western form is almost invariably rhomboid. He states 

 that it is bluish-white within, with a white margin. The eastern 

 form is sometimes colored within in this way ; in the western speci- 

 mens the border is generally darker than the rest of the interior. 

 The length given, 2\ inches, agrees better, I think, with the eastern 

 shell than with the western one, which runs from 3 to A\ inches, 

 though of course Say might have had a young specimen of the heavy 

 rhomboid form before him. 



He says that it was communicated to him by Mr. Lea, who found 

 it in the Scioto River. I am doubtful whether Dr. Lea ever col- 



