332 THE CHICAGO ACADEMY OF SCIENCES. 



the center; operculigerous lobe oval, broader than the foot; 

 operculum horny, thin, subspiral, striated spirally and longi- 

 tudinally, except on the older part which is striate spirally 

 (Fig. 118, i); rostrum short, broad, emarginate in the middle; 

 tentacles long and slender, cylindrical, blunt; eyes placed at 

 the inner base of the tentacles, in front of a prominent tuber- 

 cle; mantle simple on the edge; verge placed on the right side 

 of the back, behind the right tentacle, bifid, one part being 

 short, thick and truncated at the extremity, and the other long, 



FIG. 118. 



AMNICOLA LIMOSA Say. (1, Binney, Fig. 159; 2, 3, Stimpson, Fig. 7.) 

 1, operculum; 2, 3, egg-capsule, dorsal and side views. (Enlarged.) 



pointed, and partly coiled about the first, generative organ in 

 the female generally found "at the junction of the body with 

 the mantle, a short distance within the margin of the latter"* 

 (Fig. 119). 



"The ova are deposited, in this latitude, during the months 

 of April and May. The ova-capsule is thin, corneous, of a 

 semilenticular shape, and attached by the cut face of the lens, 

 which forms the base. The free limb is margined with a broad, 



A 



FIG. 119. 



Animal of AMNICOLA LIMOSA Say. Enlarged. (Stimpson, Figs. 1 

 and 2.) 1, dorsal view; 2, ventral view. 



thin lamina of the same delicate, horny texture as the envel- 

 ope of the capsule itself. In size these ova-capsules are a 

 little larger than the head of the animal. They are deposited 

 singly and each contains but a single egg, which floats freely 



*The writer must acknowledge his indebtedness to the splendid work of Dr. William 

 Stimpson (Researches upon the Hydrobiinae, etc.), from whose pages much information has- 

 been gleaned. (See pp. 13-16). 



