50 TIIE NAUTILUS. 



whorl. The sculpture of this shell is somewhat suggestive of the 

 rough burr-like appearance presented by some of the Jamaican 

 Choanopomas. A series of chestnut-brown spots circling the outer 

 expanded peritreme probably indicates in fresh specimens parallel 

 rows of similar spots upon the whorls. Operculum unknown. 

 Collected by Mr. Jarvis near Ewarton, Jamaica. 



THE TJNIONID.E OF NORTH AMERICA. 



BY H. VON IHERING. 



Entering into consideration of particular species, I would make the 

 following observations : 



Quadrula spheniopsis Morel certainly does not belong to the 

 genus Quadrula, because the female is inflated in the same manner 

 on the base of the shell as Lampsilis. I have a good series of speci- 

 mens, some of which were examined by the late Dr. Fischer. I sub- 

 ordinate this species to the genus Nephronaias, of which Pachynaias 

 Crosse and Fischer is a synonym. 



Quadrula pernodosa Lea. I consider that this is not a variety of 

 pustidosa, because the form is quite different from that of the varie- 

 ties of pustulosa, which is always more quadrate, while pernodosa is 

 of an elongate, higher form, with more prominent beaks. The hinge- 

 line is longer in pustulosa. The distance of the large pseudocardinal 

 tooth from the end of the lateral is more than a half of the height in 

 pustulosa, but is less in pernodosa. 



Lampsilis occidens Lea, I consider as a good species, different 

 from L. ventricosus by the more central position of the beaks and 

 different shape of the anterior extremity. I have males and females 

 of both ventricosus and occidens. 



Lampsilis pictus Lea, is perhaps the male of perdix Lea. 



Lampsilis sapperi sp. n. This is the shell mentioned by Simpson 

 in his Catalogue, p. 571, n. 4, as a doubtful variety of L. explicatus. 

 The shell is more elongate, with the ventral margins sinuate and the 

 anterior extremity lower and somewhat obliquely truncate on the 

 inferior part of the anterior margins. The pseudocardinals are very 

 stout, one in the right, two in the left valve. This differs remarkably 

 from L. explicatus as figured by Crosse and Fischer, pi. 61, fig. 1, of 

 the Moll. Mex., having the pseudocardinals elevated, compressed. 



