24 CONCHOLOGY. 



by a ligament to another, which is blended with the tube ; 

 this distinguishes it from the Aspergillum. Found in sand 

 and coral. 



Shell oval, very slightly elongated, striated longitudinally, 

 slightly irregular ; equivalve, inequilateral ; hinge a little va- 

 riable ; ligament exterior ; two well-marked distant muscu- 

 lar impressions ; a calcareous sub-cylindrical tube, more or 

 less completely surrounding the shell, and terminated before 

 by a single orifice. 



C. aperta. The open Clavagella. 



Tube erect, adhering ; aperture waved, entire, expanding, 

 funnel-shaped, leaving the two valves open or uncovered in 

 all their anterior part ; with an ovate face valve. 



3. Fistulana. Four species. 



Lamarck asserts that the tube and shell of this genus are 

 quite distinct. It so greatly resembles the Teredo that it is 

 with difficulty distinguished. It is found in sand, wood, 

 stone, and sometimes shells. 



Shell annular or very short, not sharp nor angular anteri 

 orly, but in other respects much like that of the Teredo. 



Tube generally shorter, thicker, more solid, more club- 

 shaped than that of the Teredo, always closed at its anteri- 

 or extremity in such a manner as to contain and entirely 

 hide the shell ; the posterior extremity open, and divided in- 

 teriorly into two syphons by a partition. 



Fistulana clava. Fistulana gregata. 



F. corniformis. F. lagenula. 



F. corniformis. The horn-shaped Fistulana. 

 Answers to the above description. 



F. gregata. The gregarious Fistulana. 

 Sheath or tube doubly club-shaped, congregating ; shell 

 angularly arcuated, with double angulated serrated wings. 



F. Clava. The Club Fistulana. PL 33, fig. 5. 

 Species with one end clavate, the other incurved, narrow- 



