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TRANSACTIONS OF THE SECTIONS. 75 
Cliona (although using the same solvent) destroy the shell of the Saxicava, as both 
were capable of wearing the oyster-shell, because the Saxicava was protected by an 
epidermis, —a membrane which he presumed was given to mollusca in general for the 
specific purpose of defending the shel] from the corroding action of the carbonic acid 
contained in the water in which they exist. 
The author also mentioned an instance of two specimens of Saxicava found by him 
boring in the valve of an oyster, the one at right angles with the other, the one which 
met the other full on the side being flattened by the contact; this circumstance, to- 
gether with the wound caused being still in apposition, clearly proves that neither 
has advanced or moved during a considerable portion of their existence ; moreover a 
portion of the shell into which they have bored opposite to the opening of the mantle, 
as stated before, remains prominent, so as to stand between the anterior edges of the 
two valves, proving beyond a doubt the impossibility of the animal's capability of ro- 
tating upon its own axis. 
Of the boring of Patella, the author argued that its form will preclude all idea of 
its boring by the action of its shell. 
His observations upon the boring of the Buccinum into the shells of other mol- 
lusca attributed their power of perforation to the same source, that is to a current 
charged with carbonic acid passing through the buccal apparatus of that tribe, the 
lingual riband having no part in the operation; the portion of the incomplete per- 
foration which would most correspond with this siliceous apparatus was left the most 
prominent part. The animal, he stated, takes about two days to perforate the shell of 
the common mussel, and performs the work without the least action on the part of 
the shell, as must be the case whenever a circular hole is bored by mechanical action. 
The same theory he presumed will hold in the absorption of the columella in the 
family of the Purpuriferze ; that which follows the long-continued residence of the 
Pagurus in the shell of Trachelipods : as also the groove sunk by 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 shell, it absorbs it equally with any 
other.” 
Upon the boring of Teredo he had nothing new to offer, never having had an op- 
portunity of examining any but dead animals in. old wood; he believed that their 
anatomy being so different from the mollusca which bore into clay and stone, would 
account for a different action on the part of the creature, except in Xylophaga, which 
being free, bored probably, as it is presumed, the Pholas bores; in this idea the author 
is, he argued, supported by the fact that this animal rarely boves more than an inch 
deep, and that only into saturated wood, invariably shunning the harder kinds. 
_ The Prince of Canino made a few remarks on the characters which distinguish the 
little Blue Magpie of Spain (Pica Cookii) from that of Siberia (Pica cyanea, Pallas). 
He also stated that the new Caprimulgus of Hungary belonged to the genus Cordylis, 

On the Genera of British Patellacea, By Prof, E. Forzzs, F.R.S. 
The great similarity existing between pateiliform shells, the animals of which are 
so different that they cannot be included in the same genus, has long been known 
to naturalists, and is one of those apparent anomalies which have been laid stress 
upon as sources of uncertainty in palaontological inductions: without however very 
good reason, for the remains of the mollusks in question are rarely found in the fossil 
state, and the great majority of fossils of that class of animals are such as can be con- 
fidently depended on. In the course of the researches undertaken by the author and 
Mr. Hanley for their joint work on the “ History of British Mollusca,” now in progress 
of publication, a fresh inquiry was required to be made into the propriety with which 
the British Patellacea had been assigned to known genera. It resulted that among 
our species we had two forms, for which it becomes necessary to construct new ge- 
" neric types, viz. the so-called Lottia fulva and Lottia ancyloides, Neither of these 
- belong to Acmea, with which Lottia is synonymous, but both differ essentially in cha- 
racters of head, mantle, dentition, and in the latter case, position of body with respect 
- to shell, As no established genus can receive them, for the former a new genus, 
