CLAVAGELLA. 



In habit. Clavagella consists of a shelly tube or sheath, 

 rather attenuated and open anteriorly, irregularly ovate, 

 subcompressed^ clavate and closed at its lower extremity, 

 excepting by a number of irregular minute tubes: in one side 

 of this clavate extremity an irregular, thin, flattish, pearly 

 valve is fixed; another, also extremely irregular, is foun^ 

 loose in the bottom of the tube ; this valve we have reason 

 to think is united to the fixed valve by means of a ligament 

 when the animal is living; for, we observe, what we con- 

 ceive to be the remains of such a ligament at one edge 5 

 there is also near one side an irregular muscular impres- 

 sion. The external appearance of the lower part of the 

 tube could not be shown in the principal specimen, because 

 of its being surrounded by earthy matter; we have there- 

 fore copied one of Lamarck's figures of CI. echinala, 

 which shows the outside of the attached valve and the 

 spiniform tubes very distinctly, the specimen from which 

 this has been drawn is evidently broken at its upper end, 

 and, therefore, does not show the foliaceous reflected edge 

 of the aperture of the tube, which led to the discovery ol 

 the real nature of the specimen in the British Museum. 



The tube of Clavagella appears, like that of Gastro- 

 chasna, sometimes to be free, and sometimes to line cavi- 

 ties formed in submarine bodies by the animah 



Fig. 1. Clavagella apcrta. 



2. Its aperture seen from above. 



3. Outside of the loose valve. 



4. Inside of the same. 



5. Clavagella echinata, Lam. ' 



t 



