30 



VIVIPARA. 



Fig. 50. 



Vivijyara coarc- 

 tata. 



the middle, and again widening at its posterior portion. First twelve or 

 fourteen rows translucent brown in color, the rest colorless. 

 "This specimen was filled with fully developed young." 



Vivipara coarctata, Lea — Shell smooth, ovate, compressed, thick, 

 imperforate, olive color ; spire drawn out ; sutures much impressed ; whirls 

 flattened ; aperture rather small, ovate, white. 



Alabama. E. Foreman, M. D. Cabinet of Dr. Fore- 

 man. Diam. .50, length .98 inch. 



This species, of which a single specimen only was re- 

 ceived, difi'ers from all of the genus which has come un- 

 der my notice. It is remarkable for its compressed form, 

 the body whirl being quite flattened. The apex is eroded, 

 which prevents the number of whorls being ascertained : 

 there appear to be five. The aperture is less round than 

 usual in this genus, and may be rather more than half 

 the length of the shell. (Zea.) 



Paludina coarctata, Lea, Tr. Am. Phil. Soc, IX, 30 (1844); Obs. IV, 30 ; 



Proc. II, 243 (1842). 

 Paludina lima, Anthont, Proc. Acad. N. S. Phil. 1860, p. 70. 

 Paludina exilis, Anthony, Proc. Acad. N. S. Phil. 1860 p. 71. 

 Paludina compressa, Lewis in Sched. (Unpublished.) 



Having before me the original specimens of Fal. lima and exilis, 

 kindly loaned me by Mr. Anthony, and one determined by Mr, 

 Lea to be his Pal. coarctata, I cannot hesitate in uniting them 

 under one specific name, which, of course, will be the earliest 

 published. No. 886T of the Smithsonian collection is also a 

 specimen of the same, though presented by Dr. J. Lewis under 

 the unpublished name of Fal. compressa, Lewis. 



As Mr. Lea's original specimen is imperfect, I have added to 

 the figure of it (Fig. 50) one of a perfect specimen 

 from his collection (Fig. 51). I am able also^to 

 add figures of the shells from which Mr. Anthony 

 drew his description of Fal. lima (Fig. 53) and 

 exilis (Fig. 52). The latter shell is rather more 

 slender than the other forms, one specimen being 

 only thirteen mills, wide, though thirty-one long. 



The striae or growth, very much decussated by 



revolving deep cut lines, distinguish all the forms 



mentioned in the synonymy, and constitute one of 



the chief characteristics of the species. 



In addition to the localities given in the various descriptions, 



I have received the shell from Natchez, Jackson, Mississippi, and 



Fig. 51. 



