m 
CLAVAGELLA Lamarck. 
Gen. Char. A bivalve whose valves are contained 
within a shelly vagina, with the surface of 
which one of them only is incorporated ; va- 
gina claviform, furnished with tubes about its 
larger end. 
Until the recent species of this Genus was discovered 
there remained some room to doubt the fact of one of 
the valves of the shell being united to the shelly tube, 
a want of symmetry that is very difficult to admit with- 
out good evidence, and to which we know of nothing 
analogous. The two Genera of the same family be- 
tween which this would naturally arrange, are Asper- 
gillum (commonly called the Watering-pot) and Gastro- 
chcena, which probably includes all the Fistulanae of 
Lamarck that really have shelly tubes, and do not be- 
long to Teredo) : the first of these has two equal valves, 
both so united to the tube as to form part of it, the latter 
has both the valves loose and also equal ; thus the cir- 
cumstance of one valve being attached is very remark- 
able. The form of the valves in Clavagella and also 
in Aspergillum is somewhat like those of Mya : the two 
Genera, however, differ in the tube, that of Aspergillum 
having besides a fringe of tubes a number of simple 
perforations in a convex disk, which do not exist in 
Clavagella : in most of the species of Clavagella the 
small tubes are irregularly scattered over the larger end 
of the principal tube or vagina, but in one they are in a 
circle and regularly branched ; this species consequently 
leads to Aspergillum. Most of the species require to 
be attached to some solid body for their support, or are 
imbedded in porous stones : some, however, seem to be 
free, and not one probably is capable of boring a hole 
for itself, as all the Gastrochoenae and the Fistulanae do. 
We have shortened the Generic Character in conse- 
quence of its being too precise a description of one spe- 
cies, but trust it is still sufficient to exclude every other 
Genus. 
* See Sowerby’s Genera of Shells, “ Clavagella aperta.” 
