290 Dr. W.C. M‘Intosh on the Boring of certain Annelids. 
codore ciliata, but did not enter into the modus operandi. M. 
Marcel de Serres * describes the genus Stoa, one of the chief 
characteristics of which is that it perforates West-Indian shells 
—a fact, however, which had previously been observed by other 
naturalists. M. Valenciennes +, in his remarks on the per- 
forating Echinz, instances the case of a Sipunculus that bores 
wood. M. Lacaze-Duthiers { describes, in a careful paper, 
Bonellia viridis, a Gephyrean which bores calcareous rocks on 
the shores of Corsica. Prof. Grube § has lately described two 
other forms beside that first mentioned, viz. Sabella saxicola 
and Phascolosoma verrucosum, which perforate the limestones 
of Martinsica and the island of Lussin in the Adriatic. 
The chemical theory in regard to such borings, it is well 
known, has frequently been brought forward by zoologists in 
the instances of Mollusca and Sponges, and lately has even 
been assumed with regard to the Bryozoa||. Moreover it 
has more than once been promulgated to explain the means 
whereby Annelids perforate shells and rocks. Besides those 
already alluded to, Mr. Osler, for instance, brings forward the 
case of the Annelids to show that a shell is not essential to 
the boring-process, and in support of the solvent theory; yet 
he could not find any such agent in the animals. Like his 
successor Mr. Lankester, he gets over the “ argillaceous”’ dif- 
ficulty by averring that they do not bore in this material, but, 
more fertile in resources, he hints that they probably inhabit 
cavities bored by other animals]. A.S. CErsted considered 
that Dodecaceria concharum bored partly by aid of the secre- 
tion of its alimentary canal (which, says he, contains muriatiec 
acid), and partly by aid of its hooks. Sir J. Dalyell** likewise . 
thought that the tube of this animal might be enlarged by 
some solvent. Mr. Spence Batett accounts for the majority 
of marine borings by an ingenious theory which adroitly 
shifts the onus of the solvent from the animal itself to its sur- 
roundings ; or, in other words, he avers that the solution of the 
difficulty and the rock is achieved by the agency of free car- 
bonic acid held in solution by sea-water. He instances “ the 
groove sunk by the Spiroglyphus, which Annelide affords a good 
example to illustrate the theory ; for it not only sinks a groove 
in the shell on which it has erected its own, but, should its 
contortions bring it into contact with any portion of its own 
* Ann. des Sc. Nat. sér. 4. tom. iv. 1855, p. 230, pl. 8 c. figs. 1-8. 
+ Compt. Rend. Acad. Sc. Paris, tom. Ixi. 1855. 
{ Ann. des Se. Nat. sér. 4, Zool. tom. x. p. 49, pls. 1-4. 
§ Ein Ausflug nach Triest und dem Quarnero, pp. 47, 48, 1861; and 
Die Insel Lussin u. ihre Meeresfauna, 1864. 
|| Ann. Nat. Hist. ser. 3. vol. xvii. p. 472. 
4] Phil. Trans. 1826. *% Pow. Creat. vol. 11. p. 210. 
+t Transact. Brit. Assoc. 1849, p. 73-75. 
