Mr. J. W. Williams on a new Species of Ampullaria. 47 
duced on a much lower plane, as shown in a side view of the 
prosternum (fig. 2). 
The prosternal strie join in front and the keel at the coxe 
begins to widen out gradually to its base. The apices of the 
anterior femora (shown in fig. 1) are grooved in a remarkable 
manner and are built up with semicircular edges, and the 
grooves are very finely but very distinctly transversely 
striate. 
Hab. San Estaban ; taken in March 1888. 
Idolia integra, n. sp. 
Orbicularis, perconvexa, picea, nitida, pedibus antennisque rufis ; 
fronte subtilissime et minutissime strigosa, margine elevato, antice 
haud interrupto; pronoto, stria marginali integra, elevata, late- 
raliter distincte sinuato; prosterno minutissime strigoso, lateraliter 
striato; mesosterno stria antice integra metasternoque disperse 
punctulatis; pygidio levi. 
Long. 2 mill. 
Hab. San Estaban. 
This species is exceedingly like Jdolia gibba, Lewis, but 
the mesosternal stria is complete in front and the two sternal 
plates are distinctly punctulate. In Ldolia gibba the meso- 
sternal stria terminates on each side at a point opposite the 
prosternal stria, and is therefore widely interrupted, and it is 
at present the only described species in which it is so. 
V.—WNote on a new Species of Ampullaria from the 
La Plata. By JosepH W. WILLIAMS. 
Mr. W. D. Georce, of Charlton, has recently sent me an 
Ampullarian which he collected in October 1888 from some 
marshes near the La Plata, at Buenos Ayres, in the Argen- 
tine Republic. I have, in company with Mr. Edgar Smith, 
examined the species belonging to this genus which are in 
the National Collection, and not found one to which this 
present shell could be referred; I have also looked over 
the various literature known to me on the genus, and have 
found no description which could be applied to this form. I 
therefore name it (provisionally at any rate) Ampullaria cana- 
liculata, for a reason which will be readily noticed in the 
following description. 
The shell is large, solid, and thick. Its length is 6 centim. 
