149 



between them. The present is smaller and proportionally more 

 slender, and the spire is more attenuated. 



Note. — Bulla fluviatilis, nob., seems to be no other than the very 

 deceptive young of our common Planorbis. 



Anoylus tardus. — Shell conic depressed : apex behind the 

 middle obtuse, rounded, inclining backward but not laterally : line 

 from the apex to the posterior tip rectilinear ; line from the apex 

 to the anterior tip arquated : aperture oval, not distinctly narrowed 

 at one end. 



Length, a little over three-twentieths 4-25 ; breadth, one-tenth 

 of an inch. 



Differs from A. rioularis, nob., which has the apex leaning 

 towards one side, and the aperture narrower at one end. It is less 

 elongated than fluviatilis, Drap., which has an acute and laterally 

 inclined apex. 



It inhabits the Wabash River. 



[No. 6. Transylvania Journal of Medicine, vol. 4, p. 525, etseqq. 1831.] 



UnIO INTERRUPTCS, UnIO GLEBULUS, 



" nexus, ^ " declivis, 



Unio lapu,lus. 



[The descriptions of these species were afterwards repeated fn the 

 "American Conchology." For the sake of greater convenience they 

 will be found under that head. They were not included in Mrs. Say's 

 " Descriptions." — Ed.] 



[No. 7. American Conchology.] 



[Am. Con., part 1, 1836.] 



AsTARTE. — Shell suborbicular, generally transverse, equivalve, 

 ingequilateral, closed entirely ; hinge with two strong, distinct, di- 

 verging teeth on one valve, and on the other two very unequal 

 teeth and a lateral obsolete one ; ligament exterior ; muscular im- 

 pressions two, and a minute one above the posterior impression, 

 almost confluent with it ; impression of the mantle simply arquated, 

 distinct. 



* [No description already included in my reprint will be repeated here, 

 but any additional remarks, &c., will be given. — Ed.] 



