MR. BRODERIP ON CLAVAGELLA. 267 
of the supposed solvent, as well as the organ for applying it, may be so placed as that 
the solvent shall only come in contact with the inorganic or dead substance to be acted 
on, without touching the shell. 
Again, it has been asked, what solvent would act equally on a calcareous and on a 
siliceous substance? To this it may be answered, first, that it is not pretended that 
the nature of the supposed solvent is known ; secondly, that, in siliceous grits, there 
is more or less calcareous matter by which the mass is held together, and that the so- 
lution of the calcareous particles would be followed by the disintegration of the stone. 
The fossil species are numerous, and as yet do not appear to have been detected be- 
low the supracretaceous group. One observation, arising from the various depths at 
which the recent species have been found, will not perhaps be deemed irrelevant. Clav. 
Australis was so near the surface at low water, that it was detected by its ejection of 
the fluid ; Clav. elongata, from the nature of the coral in which it is chambered, could 
not have been living far beneath the surface ; whereas Clav. lata was dredged up from 
a depth of sixty-six feet. Any inferences, therefore, as to the state of submersion of a 
rock during the life of the fossil species of Clavagella which there occur, should be made 
with caution by the geologist. 
In conclusion, it may be observed, that though this genus is now rare in cabinets, it 
is, in all probability, widely diffused ; and collectors cannot be too astute in examining 
masses of coral and submerged perforated rocks, with a view to the further elucidation 
of the habits and structure of these interesting animals. 
PLATE XXXV. 
Figg. 1, 2. The interior of the two parts of Mr. Goldsmith’s specimen of Astreopora, 
containing two individuals of Clavagella elongata. The several points 
represented at «, 8, y, 5, come in contact when the two parts are placed 
together. 
. Anterior wall of the cavity in which the larger individual is situated. 
. Broken termination of the posterior tube or siphonic sheath. 
. Anterior portion of the cavity of the smaller individual. 
. Portion of a cavity occupied by a Petricola. 
. Anterior edge of the wall of the coral chamber. 
. A broken group of Serpule. 
- Insulated shelly plate, with tubular perforations at the anterior end of the 
ovate chamber. 
a’. Fixed valve imbedded in the coral. 
2. «. Cavity of the smaller individual. 
+. Perforated shelly plate of the anterior ventral edge. 
VOL. I. 2N 
eo wk De Qa 
