The priority of the demonstration of the Pholas and its "boring habits" has been much disputed. The evidence is full of curious details. It appears that Mr. Harper, of Edinburgh, author of "The Sea-side and Aquarium," having claimed the lead. Mr. Robertson, of Brighton, writes to dispute the originality; adding that he publicly exhibited Pholades in the Pavilion at Brighton in July, 1851, perforating chalk rocks by the raspings of their valves and squirtings of their syphons. Professor Flourens (says Mr. Robertson) taught my observations to his class in Paris in 1853; I published them in 1851, and again more fully in the "Journal de Conchyliologie," in 1853; and M. Emile Blanchard illustrated them in the same year in his "Organisation du Règne Animal." I published a popular account of the perforating processes in "Household Words" in 1856. After obtaining the suffrages of the French authorities, I have been recently honoured with those of the British naturalist. (See Woodward's "Recent and Fossil Shells," p. 327. Family, Pholadidæ.) On returning to England last autumn I exhibited perforating Pholades to all the naturalists who cared to watch them. An intelligent lady whom I supplied with Pholades has made a really new and original observation, which I may take this opportunity of communicating to the public. She observed two Pholades whose perforations were bringing them nearer and nearer to each other. Their mutual raspings were wearing away the thin partition which separated their crypts. She was curious to know what they would do when they met, and watched them closely. When the two perforating shell-fish met and found themselves in each other's way, the stronger just bored right through the weaker Pholas.[28] Mr. Robertson has communicated to "Jameson's Journal," No. 101, the results of his opportunities of studying the Pholas, during six months, to discover how this mollusc makes its hole or crypt in the chalk: by a chemical solvent? by absorption? by ciliary currents? or by rotatory motions? Between twenty and thirty of these creatures were at work in lumps of chalk, in sea-water, in a finger-glass, and open for three months; and by watching their operations. Mr. Robertson became convinced that the Pholas makes its hole by grating the chalk with its rasp-like valves, licking it up when pulverized with its foot, forcing it up through its principal orbrambial syphon, and squirting it out in oblong nodules. The crypt protects the Pholas from _confervæ_, which, when they get at it, grow not merely outside, but even with the lips of the valves, preventing the action of the syphons. In the foot there is a gelatinous spring or style, which, even when taken out, has great elasticity, and which seems the mainspring of the motions of the Pholas. Upon this Dr. James Stark, of Edinburgh, writes: