138 DUBLIN NATUEAL HI8T0EY SOCIETY. 



rent parts of the animal before us. The head is contained within two plates of 

 shell, carved in the most elaborate manner, and held together by ligament and 

 cartilage of a very complicated structure, the cartilage forming sockets into 

 which the several rounded processes are inserted, and which enable the animal 

 to move the plates in a somewhat similar manner to those animals possessing the 

 ball and socket joint. From those plates the worm springs, attaining a great 

 length, and terminating with two palette-like plates of shell, termed the caudal 

 appendages. It is by those plates that the different species of Teredines are 

 distinguished — Teredo navalis being deeply notched, but T. Norvagica, our 

 species, having the palette entire. 1 have stated that the animal attains a great 

 length ; I have seen it, when contracted, measuring eighteen inches ; it would 

 exceed that considerably if in its natural state. It appears to be filled with the 

 wood excavated, which is reduced to an impalpable pulp ; the microscope will 

 determine whether it is so or not ; but the most singular portion of the struc- 

 ture or domicile is the calcareous tube, which the animal secretes from the mo- 

 ment he enters the wood, and in which he subsequently lives ; its length appears 

 to be limited only by the length of the timber ; the fine specimens on the table 

 will demonstrate the mode of deposition. There are many points of interest un- 

 touched connected with this mollusc, which would occupy more time than can be 

 afforded at present, but which, I trust, I shall be able at some future period to 

 bring before the Society. I now have great pleasure in laying the results- of my 

 investigations before the Society, and exhibiting, in propria persona, the speci- 

 mens obtained amongst some turf inhabited as I have described ; and, in addi- 

 tion, a specimen of Pholas dactylus, which, although not of large size, suffi- 

 ciently attests its existence, and the probability that it will be found of full size, 

 and in eqnal abundance as the others, when favoured by a low tide. This spe- 

 cimen I obtained shortly before the following incident: — In the middle of July, 

 1850, perceiving a very low tide, I took a spade, and, going down to the strand, 

 commenced my "diggings," not, as you may perceive, in a golden vein, but in 

 the humble bog ; nevertheless, on counting up my gains on the returning tide, I 

 found, to my great delight, not an ounce of gold dust, but a noble specimen of 

 Pholas papyracea, now on the table. I feel that I am safe in asserting, both that 

 I prefer that discovery to many ounces of gold, and that it was the first time 

 it ever was found in Ireland, and thus that an addition to the Fauna of our island 

 has been made. As if to give an additional interest to this discovery, I was 

 shortly after favoured by a visit from Professor Edward Forbes, who accompa- 

 nied Sir Henry de la Beche on a geological excursion to my neighbourhood. 

 He said it was the finest specimen he had seen; and Sir Henry de la Beche ob- 

 served that it was typical of the red marl of Devonshire. This observation 

 should be held in remembrance, as Waterford partakes not only largely in its 

 geological structure with Devon, but also in its mollusca. It will be seen from 

 the above statement that we have four members of the very natural family of 

 Pholadiae, associated with Teredo Norvagica and Pullastra perforans, occupying 

 the same ground, and vying with each other for the maintenance of their free- 

 hold. I think this a favourable opportunity of observing, that the mode by 

 which the Pholadiaj sink into the turf or wood, and subsequently enlarge the 

 orifice upwards, is two-fold. There can be no doubt that the foot is the instru- 

 ment by which the mollusc works its downward passage through the turf or 

 wood, and that the tongue or tube subsequently enlarges the orifice upwards, 

 and thus secures a free communication for that organ with the water from which 

 it derives its support and nutriment. This view, I conceive, will be apparent, 

 by examining the shell in situ now on the table. It would be out of place here 

 to discuss the modus operandi employed by the animal in this rather complex 

 motion, so I shall proceed to draw your attention to another class of borers, or 

 Lithodomi, who apparently have a much more difficult task to perform in ob- 

 taining a habitation in the living rock. It must have occurred to the majority 

 of those present to have seen on the . sea-shore, and frequently in fancy rock- 

 work, limestone boulders perforated in such a manner as to resemble a sponge. 



