8 LAXD AND FRESH-WATER SHELLS OF N. A. [PART IV. 



Observations. — This species resembles very much the lo fusiformis 

 (nobis), Fusus fluviatiUs, Say, but maybe distiuguished by its large, 

 trausverscly compressed spines, tlie fusiformis having some longitu- 

 dinal tubercles. I am not acquainted with any fluviatile shell which 

 has such large spines (thei'e being about seven on each whorl), nor 

 any which has such a general resemblance to a marine shell. 



Prof. Troost informs me that they ai-e rare in the river, that they 

 had been observed in the graves of the aborigines ; and as it was 

 generally believed that these were " conch shells," consequently 

 coming from the sea, it was urged that the inhabitants who possessed 

 them must have come over the sea. It does not appear that they had 

 been observed in their native element, though living at the very doors 

 of the person who had remarked them in the tumuli. — Lea. 



The accompanying figure is from a half-grown specimen in 

 _,. „g the Smithsonian Collection. In the shells de- 

 scribed by Mr. Reeve, quoted in the above syn- 

 on3Mn3^, I cannot recognize specific characters, 

 although lo recta may possibly rank as a variety. 

 The descriptions of the various synonymes are 

 appended, with figures from the type specimens. 



lo gibbosa. — Shell stoutly fusiform, fulvous ; whorls 

 rudely obliquely plicated, ob- 

 tusely tubercled in the middle, last whorl '^" ' 

 spirally plicately ribbed around the lower 

 part, rib swollen, gibbous; columella arcu- 

 ately twisted, canal broadly effused. 



Habitat. — Southern United States. 



Observations. — The gibbous ridge which 

 encircles the lower portion of the body- 

 whorl of this species "is not," Avrites Mr. 

 Anthony, "a mere accidental aberration; I 

 have seen othei's like it." — lieeve. 



The extensive suite of sj^inosa that 

 I have examined proves that the gib- 

 bous ridge is " a mere accidental aber- 

 ration," being found in all stages of 

 development on specimens which are otherwise distorted in 

 growth, as Mr. Anthony's type, figured above, undoubtedly is. 



