112 ON THE NAIADES, 



lamellar; cicatrices smooth, impressed, showing the mark of their ad- 

 vancement ; palleal impression indistinct, broad ; cavity of the shell 

 rather shallow ; cavity of the beaks angular ; nacre yellowish white and 

 shining. 



Remarks — This is certainly a very interesting shell. It is difficult 

 to find any one to compare it with. On the inside of the anterior 

 margin there appears to be a disposition to crenulation, caused by the 

 longitudinal striae. Its habitat I am not acquainted with, having pur- 

 chased my specimens at a dealer's in Europe, who could not inform 

 me from what country they came. 



Jo spiNOSA. Plate XIX. fig. 79. 



Testd obtuse turritd, laid, corned, sub epidermide fasciatd, spinis magnis ; an- 

 fractibus septenis ; aperturd elongatd, dimidiiim longitudinis tesise habente. 



Shell obtusely turrited, wide, horn colour, under the epidermis banded, furnished 

 with large spines ; whorls seven ; mouth elongate, one half the length of the shell. 



Hab. Holston River, Washington County, Virginia. Professor 

 Troost. 



My Cabinet. 



Cabinet of Professor Troost. 



Diam. 1-2, Length 2-2 inches. 



Remarks. — This species resembles very much the lo fusiformis 

 (nobis), Fusus Jiuviatilis (Say), but may be distinguished by its large 

 transversely compressed spines, the fusiformis having somewhat longi- 

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

 has such large spines (there being about seven on each whorl), nor any 

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

 Troost informs me they are rare in the river, that they had been 

 observed in the graves of the aborigines ; and as it was generally be- 



