40, THE NAUTILUS. 
descriptions to those of the published species. I fail to discover the 
identity of Valvata mergella, Westerlund with Valvata striata, Lewis. 
The proportions of the shell, number of whorls, elevation of the 
spire, ete., etc., are not the same in the two species. I must add that 
Dr. Westerlund was certainly acquainted with either Valvata scncera 
or striata, as in the description of his merged/a, he alludes to the 5 
already described North American forms! 
I have recently described under the name of Liogyrus Lehnert, 
a shell that was sent me some five years ago, by Mr. E. Lehnert, who 
discovered it in the Potomac, together with Gould’s shell. The 
operculum which I have not seen, proved to be Amnicoloid, hence the 
species should be called Amnicola Lehnerti. It is a sinistrorse, not 
“distorted” shell, and owing to the number of specimens already 
known, it may be termed a constant form, for not counting my two 
typical examples, Mr. Lehnert sent some to Mrs. Geo. Andrews, who 
wrote about these, saying in was “indeed an interesting shell,” and 
besides those he undoubtedly possesses in his own cabinet, Mr. H. A. 
Pilsbry saw others that permitted him to ascertain its generic position. 
Distorted specimens are frequent, as the latter says, in fluviatile 
shells, but sinistrorse monstrosities are very scarce, and hitherto two 
or three species at most (Limnea peregra, Melantho decisa), normally 
dextral, have been found sinistral, and amongst these no Ammnicola, 
although specimens of this genus are profusely distributed in suit- 
able stations in Southern Europe, North Africa and North America. 
I hunted much for fluviatile shells in Europe, but never gathered 
any sinistral Amnicolze and other fluviatile species, and frequently 
occurred to my notice trochoid or distorted specimens of Planorbis, 
some with part of the whorls entirely loose from the preceding ones ; 
this I observed in Planorbis nautilius, Planorbis complanatus, and 
some of the allied species, also in a wonderful little shell found in 
1884 by myself in the river named “Gave de Pau” in 8S. W. 
France, and perhaps a Paladilhia. (1 never attempted to describe 
this single specimen, no other species of Paladilhia, having ever 
been discovered not even in that location by myself, but in that part 
of France, by other naturalists ; hence I should reasonably suppose 
it is really new, as it is different from the other Paladilhie not only 
in this character, the last whorl being entirely detached, but still in 
shape.) The genus Liogyrus, Gill or “ Lyogyrus” appears to 
possess this only conchological character (the last whorl loose from 
the preceding), by which it may be distinguished from some of the 
