THE NAUTILUS. 
59 
author recognizes two species of Tulotoma (magnified and coosaensis), 
four of Vivipara ( contectoides , intertexta, subpurpurea, troostiana ), 
two Lioplaces, and nine species of Campeloma. The main facts of 
the distribution and station of each species are stated, largely from 
the authors own wide experience in the field. It would be unrea¬ 
sonable to expect any discussion of synonymy in a paper of the 
scope of this one, but even if Prof. Call could prove the specific 
identity of Vivipara contectoides with georgiana, wareana, etc., why 
should he use the latest instead of the earliest name for the species ? 
—J. & P. 
Dr. Wm. H. Dall has recently issued a “ Monograph of the 
Genus Gnathodon, Gray (Rangia Desm.).” In this essay the 
priority of the name Gnathodon for the group is demonstrated ; the 
anatomy of both soft and hard parts is described, and the species are 
discussed and figured. Dali concludes thaL Gnathodon does not con¬ 
stitute a distinct family near Cyrenidce, as Fischer has it, but that it 
belongs without doubt to Mactridce and is probably an off shoot from 
the Mulinia stock. The range of the genus is “ Subtropical Amer¬ 
ica, the Gulfs of California and Mexico, in shoal quiet water, vary¬ 
ing from salt to fresh, but preferably somewhat brackish; range in 
time from the newer Miocene to recent seas.” Three sections are 
adopted, Gnathodon typical, Miorangia Dali and Rangianella Conr. 
G. cuneatus Gray is the commonest species in collections (often under 
the name Rangia cyrenoides ). 
The Mollusca of the Paris Mains. — M. Locard has been 
making some very interesting studies of the mollusks of the water- 
mains of Paris, from which he has collected forty-four species belong¬ 
ing to thirteen genera, among which several species are described as 
new to science. These are, however, only slight varieties of well 
known species. Among other peculiarities of this strange fauna he 
notes four marked modifications, due to their environment, in which 
they differ from the types in the waters from which these mains are 
supplied. These are : [1] A diminution of size, due to the absence 
of light; [2] a decrease of marked coloration, due to the same cause ; 
[3] decided modifications of form, generally producing a lengthened 
shell, due to the mechanical action of a steady and rapid current; 
[4] difference of general appearance, the polished, brilliant shell 
being developed with regularity in a constant medium. The last 
two peculiarities may be noticed in the shell life of those streams in 
tropical countries which in the shaded mountains are constant; as 
