49 



The shell is generally open as wide as the mantle and the epidermis 

 (which is folded over the edge of the shell, and is soldered to the man- 

 tle) will permit. I placed betweeh 40 and 50 shells in a tub of water 

 with a piece of strong slaty clay, but none of them attempted to perforate 

 it, possibly on account of its hardness, although kept for several days. 

 The animal at times spirts a strong stream of water from the anal siphon. 

 It inhabits cylindrical holes in clay, which it probably excavates with its 

 powerful foot which is always downwards. The holes descend to the 

 depth of half a foot and more ; I should not consider the shell, the 

 extremity of which is defended by the lapping over of the epdermis, as 

 sufficiently strong to aid in any way, except as a fulcrum for the opera- 

 tions of the foot. They are found by digging below the surface of the 

 water, in the margins of banks, where they appear to have been per- 

 forated. 



The worn shells are not uncommon in the beds of the Jumna and 

 Gumti when the waters are retiring. They are rarely found in holes in 

 canvar-rock. In this case the shell is distorted, if confined in an irregular 

 hole, to the sinnosities of which it in a measure conforms itself, thereby 

 shewing that the residence was chosen accidentally, and that the abode 

 was not formed by the animal itself. In the clay the shells are more 

 symmetrical. 



As in the Solenaceae, the edges of the mantle are soldered together at 

 the base, forming a tube which confines the animal, and gives more sup- 

 port to its muscular foot, the exertions of which are principally required 

 in the direction of the axis of the shell. In its habits Novaculina, also 

 resembles Solen, clay being merely substituted for sand, in which the 

 latter genus delights to burrow vertically. The animal differs from Solen 

 in having its siphons free, instead of occupying a common tube ; and 

 in having an expanded instead of a conical, termination to the foot. 



To Solen Ensis the shell seems, at first, to have little resemblance ; 

 but it has more characters in common with Solen Legumen, which is 

 less linear, and has comparatively prominent beaks situated towards the 

 centre of the hinge margin. In Solen Legumen, also, the ligament. 



