12 Trans. Acad. Sci. of St. Louis. 



Habitat: Found in small colonies in ditches and clear 

 patches of swamp. It prefers submerged pieces of wood. 



He?narks: This species is distinguished by its heavy spiral 

 lines and long, acute spire. The animal is very rapid and de- 

 cisive in its movements. Several specimens, kept together in 

 captivity, ate holes in each other's shell for the lime for their 

 own shells. This was at first attributed to cannibalism, but 

 upon investigation no foundation for this supposition was 

 found. It is quite abundant and is one of the neatest 

 Limnaeids found in this area. An egg mass of this species 

 was laid March 18, 1897. It contained 45 eggs, distinctly 

 nucleated, and in a jelly-like mass measuring 11 by 2 mill. 



On March 18th a second egg mass was laid and on the 19th 

 three more masses. On the 22d three individuals were seen 

 in coitu, each one endeavoring to play the active part. Of 

 the five egg masses laid each contained the following number 

 of eggs : 42, 42, 35, 45, 28. The eggs were spherical in shape 

 and very distinctly nucleated. One set of eggs was laid the 

 morning of the 19th and at noon of the 20th embryos were 

 seen slowly rotating about, propelled by numerous cilia. The 

 writer regrets that through some accident which occurred 

 while moving from one house to another, the eggs became 

 lost, so that he is unable to record any exact observations on 

 the embryology of caperata. 



This species is closely related to cubensis and might, per- 

 haps, more properly be made a variety of that form than a 

 distinct species. The spire in caperata is long and somewhat 

 pointed and the aperture is much shorter than the spire. In 

 cubensis the spire is short and conic and about equal to the 

 aperture in length. Caperata is found universally distributed 

 through the area. 



6. Limnaea cubensis Pfeiffer. 



Pi. I. f. 1 0. 



Limnaea cubensis Pfeiffer in Weigmann's Archiv. fiirNatur. 1839 : 354. 



Limnaea umbilicata Adams, Amer. Jour. Sc. i. 39 : 374. 1840. 



Limnaea techella Haldeman, Amer. Jour. Conch. 3: 194. pi. vi. f. 4. 1867. 



Shell: Ovate, solid, translucent; color yellowish or brown- 

 ish horn; surface shining, growth lines fine and numerous; 

 shell encircled by impressed spiral lines; whorls 5, very con- 



