History of British animals - University of Guam Marine Laboratory

284 MOLLUSCA. BRANCHIFERA. Tritonia.Length about a quarter of an inch, of a slender form, the front obtuse, taperingbehind, of a pale yellow, with minute pink spots; tentacula slender,filiform, with a large trumpet-shaped basilar sheath.Gen. XXXVIII. TRITONIA. — Branchial plumes in arow on each side the back, and destitute of basilar sheaths.141. T. Hombergii.— Branchiae forming a continuous plumosecrest on each side the cloak, between which and the marginof the foot, the body is compressed 2— and smooth.Cuv. Ann. Mus. i. t. xxxi. f. 1, (Limace de mer palmifere, Diquemare,Journ. Phys. Oct. 1785, t. ii.)- Firth of Forth.Length upwards of 2 inches, sometimes approaching to 8 ; of a purplishcolour. Cloak convex, thickly covered with unequal soft tubercles ; tentaculaconsisting of five plumose divisions, each surrounded at the base by aprominent ring This, the largest species of the genus, was first detected inour seas by J. G. Daly el, Esq. the learned author of the treatise on thePlanaricB.142. T. arborescens.— Branchiae, 5 or 6 on each side, in theform of plumose tubercles.Doris arb. Mull. Zool. Dan. Prod. p. 229—Fab. Fauna gr. 346. T. arb.Cuv. Ann. Mus. vi. t. lxi. f. 8-10. Flem. Edin. Encyc. xiv. 619.Length about an inch ; foot narrow, sides compressed cloak smooth, its;margin above the mouth with four plumose appendages ; branchiae decreasingin size towards the tail ;tentacula conical, transversely striated ; thesheath with a divided margin. I have found this species in the ZetlandIsles, agreeing with the characters of Cuvier, with this difference, that thebranchiae in his are only 5 on each side, while in our specimen they appearedto be 6. But as the two posterior ones are very small, and as his exampleswere preserved in spirits,it is probable that they have escaped detection. Ithas likewise been found in the Frith of Forth, by Dr Grant, who, when keepingit confined in a glass vessel, observed that it possessed the power of emitingdistinctly audible sounds.143. T. pinnatifida.— Branchiae 9 on each side, ovate andimbricated with conical papillae.Doris pin. Mont. Linn. Trans, vii. 79. t. vii. f. 2,3—Coast of Devon.Length T s 5 ths of an inch; body slender, rounded in front, tapering behind,of a grey colour, spotted with green. Tentacula filiform, with a trumpetshapedbasilar sheath. The branchiae are longer than the breadth of thethe body, and the papillae, which have black tips, are arranged in 5 or 6whorls.144. T. bifida.— Branchiae, in a single row on each side, numerous,unequal, ovate, pedunculated.Doris bif. Mont. Linn. Trans, xi. 198. t. xiv. f. 3—Coast of Devon.Length about a quarter of an inch ; body linear, acuminated behind, thefront rounded, of a whitish colour, with a reddish brown line on each side ofthe back. Sheath of the tentacula broad, erect, bifid ;behind which are twoblack eyes. Branchiae, 12 on each side, 3 in each division larger than therest, the club semitransparent, uniform on the surface, but complicatedwithin.