122 MEMOIRS OF THE CARNEGIE MUSEUM. 



L. H. D. 



Size: 1. Greencastle, Cat. No. 61.4222 (largest at hand). . .03 mm. 38 mm. 26 mm. 



2. Yardley, Cat. No. 61.3689 55 " 32 " 20 " 



3. do. do. 51 " 31 " 19 " 



4. do. do. ^ :..41 " 25 " 15 " 



Soft parts (See Ortmanp, 1912, p. 282). Glochidia (See Lea, Obs. XII, 1874, 

 PI. 21, fig. 4). Measurements: 0.36 X 0.30 mm. 



This species is also normaXly hermaphroditic, and specimens with male struc- 

 ture have never been found. Since the first publication of this fact I have ex- 

 amined several hundreds of additional specimens, but all had the female characters 

 in the gills. 



Breeding season: Gravid, females have been collected at the following dates: 

 Aug. 13, 1910; Aug. 20, 1909; Aug. 24, 1908; Sept. 5, 1909; Sept. 6, 1909; Sept. 

 12, 1912; Sept. 14, 1912; Sept. 16, 1912; then again: April 24, 1909; May 6, 

 1912; June 8, 1912. Thus the season begins about the middle of August. The 

 first date for the presence of glochidia is September 5. The glochidia are carried 



Fig. 13. 

 • Lasmigona suhviridis. 



over the winter, and discharge was observed on the last date, June 8. The species 

 is bradytidic. 



Remarks: Although this species morphologically is closel}' allied to L. viridis, 

 and is undoubtedly its eastern representative, and although the differences are 

 only in the degree of development of certain characters, it is not difficult to dis- 

 tinguish it at the first glance on account of the shape and size of shell. The range 



