MELANTHO. 53 



scarcely oblique, ovate, longer than wide, more than half the length of 

 the body whirl, within white ; peristome simple, acute, sinuose, its 

 margins not on the same plane, its terminations connected by a heavy 

 shining callus upon the parietal wall. Length of the axis 22, greatest 

 breadth of body whirl 15 ; length of aperture 15, breadth 9 mill. 



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



Proc. II, 243 (1842).— Reeve, Con. Icon. 46 a (Feb. 18G3). 

 Paludina lima, Anthony, Proc. Acad. N. S, Phil. 18G0, p. 70. — Reeve, 



Con. Icon. 46 b (Feb. 1863). 

 Paludina exilis, Anthony, Proc. Acad. N. S. Phil. I860 p. 71. 

 Paludina compressa, Lewis in Sched. (Unpublished.) 



It has beeu found iu South Caroliua, Alabama, Mississippi, 

 and Arkansas. 



The striae of 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 

 form it seems capable of some considerable variation, being, at 

 times, very slender and elongate, at others much more ovate, 

 with more globose whirls. 



I give below a copy of Lea's desci'iption, and a drawing of his 

 original specimen (Fig. 108). 



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. 8867 of the Smithsonian collection is also a 

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

 the unpublished name of Pal. compressa, Lewis. 



Mr. Lea feas enabled me to figure his original specimen (Fig. 

 108). I am able also to add figures of the shells from which Mr. 

 Anthony drew his description oi Pal. lima (Fig. 110) and exilis 

 (Fig. 109). The latter shell is rather more slender than the 

 other forms, one specimen being only thii'teen mills, wide, though 

 thirty-one long. 



Reeve places P. exilis in the synonymy of P. coarctata, but 

 considers P. lima distinct. 



Paludina coarctata, Lea. — Shell smooth, ovate, compressed, thick, im- 

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

 flattened ; aperture rather small, ovate, white. 



