THE NAUTILUS. 101 



Quadrula pusttilosa Lea. Summer breeder (Sterki, '95). 



Quadrula rubigmosa Lea. July-August (Lea, III, '42); June 

 (Baker, '98). I found this species gravid on May 27, June 30, 

 July 3 and July 8. The marsupium corresponds to the account 

 given of it by various writers; it is formed by all four gills, which 

 are at that time deep red. 



Quadrula subrotunda Lea. Summer breeder (Sterki, '95). Found 

 gravid July 3 and July 13. During late summer and fall no gravid 

 females were found, although many specimens were collected. All 

 four gills are charged and of deep red color. 



Quadr >/f a kirtlandiana Lea. One gravid female was found on 

 August 2, '07, among hundreds of specimens collected ; all four gills 

 were charged, and red. Later in the season, in August, September, 

 October, no gravid females were seen. 



Quadrula coccinea Conr. Found gravid on June 18, '08 (Nes- 

 hannock Creek, McKean Co., collected by Mr. Dennis Dally on 

 June 22, '08. There were, altogether, about a dozen of them, and 

 in every case the marsupium did not agree with the type of the 

 genus Quadrula, for only the outer gills were charged in their whole 

 extent, and were whitish. This would remove this species from the 

 genus Quadrula, and would place it with Pleurobema. (Baker, '98, 

 p. 80, gives a description of the soft parts, and says " four gills used 

 as marsupium," but this may not be founded upon personal observa- 

 tion, but may have been inferred from the systematic position of the 

 species.) 



Tritogonia tiiberculata Barn. Gravid, according to Sterki (NAU- 

 TILUS, 21, '07, p. 4<S) on June 10, '07 S and marsupium formed by 

 all four gills. This would place the species with the genus Quadrula, 

 where it would group with Q. trctpezoides Lea. Since the specific 

 name is preoccupied in this genus, and since none of the synonyms 

 are available, a new name should be found, and I propose here : 

 Quadrula tritogonia nov. nom. (I have discussed this point with 

 Dr. Sterki, and he is of the same opinion.) 



Of the other species of Quadrula found in Western Pennsyl- 

 vania, Q. hippopcea Lea, cylindrica Say, metanevra Raf., cooperiana 

 Lea, obi! qua Lea, pyramidata Lea, tiiberculata Raf., I have never 

 seen gravid females, and nothing is known about their marsupium 

 and breeding season. 



The above observations on the breeding seasons of Pennsylvanian 



