BULLHEAD, ARMED. [Asetnortiortus.] BU'LLIDiE, a family of Marine Molluscs., which Lamarck arranges among his Gasteropoda, between the Calyptracians on one side and the Laplysiana on the other, making the family to consist of the three following genera, Accra or A kera Bullcra, and Balla. Cuvier finds a situation for it in his fourth order of Gasteropods, the Tecti branchians (Monopleurobranchiana of De Blainville), which includes Lobaria quadriloba, Gmelin, which is found in almost all seas, and is very common on the shores of Great Britain, will serve for an example. The animal is whitish, more than an inch in length, and, as Curler observes, the fleshy shield formed by the vestiges of the tentacula, the lateral borders of the foot, and the mantle occupied by the shell, seem to divide it into four portions, whence Gmelin's term quadriloba. The shell is delicate, white, semitransparent, and consists almost entirely of aperture. The stomach or gizzard is armed with three very thick rhomboidal bones or rather Shelly pieces.
BtsIlwa has been found at a depth ranging from near the surface to 12 fathoms. Mr. W. Clark found three English species, two of them (Be/law cateae and B. penetata) at Exmouth and Torquay, in pooh at the time of the lowest apring-ticlee; and a third (Alike° prelim:ma) by dredging off' Budleigh Salterton. The depth is not mentioned, but it is probable that it was considerable, for the author says that it is rare, and only occasionally to be procured by deep dredging seven or eight miles from the shore. The first of Mr. Clark's species, which is Biala catena of 3[ontagu, had a testaeeous gizzard, but the gizzards of the other two were unfurnished with filially appendagcs. (See Mr. Clarke%) description, ' Zoo'. Journ.' vol. iii. p. 337). G. Sowerby, when speaking of the use of the mildly species and their powerful adductor muscles, states that the animal of Batista aperta is sometimes distorted by having swallowed entire a Corbula nucleus, which is a very thick and strong shell, nearly equal in size to itself.
Do Blainville says of this genus that he characterises it somewhat differently from Lamarck, who establishes it, and who only places under it the Acerula, whose shell is internal ; but as De Blainville considers the animal to be of the first consequence, he distinguishes under the name of BuIkea those species which, whether their shell be external or internal, have the foot thickest and not dilated into natatory appendages, having, in fact, habits different from the Bulks, according to his acceptation of the term, which swim very well and creep very badly. He divides Bulk= into 1st. Those species which have an internal shell very incompletely rolled up without spire or colu mella, and selects as his eazniple Bullcca aperta, the species figured in the preceding page.
2nd. Those species whose shell is internal and very incompletely rolled up, with a colutnella and alveolar spire (spire rentr6e), and gives as an example Bullet ampulla.
3rd. Species whose shell is internal, the lateral lobes eirrhous and more developed, and gives as • an example Ferussac's Butlaa (Quoy et Gaimard), here figured from the Atlas Zoologique' of the voyage of the Uranie.
In the Additions and Corrections' to his `Malacologie,' De Blain ville says, that, in studying more attentively the species of these two genera, it seems to him that the greater part would be better placed under Balla than under Bull ea, where lie would leave only the species which serves for the type, and another which was brought from the seas of Australia by Quoy and Gaimard. Ile then proposes an entirely new arrangement into seven groups represented by the following genera :-1. Bullina (Bulline) of Ferussac, with a projecting spire (example Balla Lajonkairiana, Bast.) 2. Aplaslre (Sebum.) 3. Bulks. 4. Aeya (Montt.) 5. The form represented by Bulks fragilis. 6. Scaphander (Montt), which is Balla lignaria. 7. Bullets (Lam.).