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Show 454 ANNELlDES. the operculum recall to our minds the foot of the Vermeti and SiJi. quarire, which have been placed among the Mollusca, the branchi~ strongly remind us of those of the Amphitrites a.nd Terebellre. Ulterior observations upon their anatomy, and principally upon that of their nervous and vascular system, will resolve this problem. The shell of some of them is angular( l ), or longitudinally stri-ated( 2). That of others is round(S). ORDER II. DORSIBRANCHIAT .£. The organs of the Dorsibranchiat::.e, and the branchire in particular, are equally distributed along the whole of the body, or at least of its middle portion. At the head of the order we will place those genera in which the organs are most completely developed. ARENICOLA, Lam.(4) Branchire, resembling small trees, on the rings of the middle part of the body only; the mouth, a fleshy and more or less dilatable pro· boscis, and neither teeth, tentacula no1· eyes visible. The posterior extremity not only wants the branchire, but the setaceous fasciculi with which the rest of the body is furnished; the cirri totally deficient. .R.ren. piscatorum, Lam.; Lumbricus marinus, L·; Pall. No1•. Act. Petrop., ii, 1, 19-29. Very common in the sand on the sea shore, where it is disinterred by the fishermen, who use it as bait. It is about a foot long, of a reddish colour, and diffuses (1) Dent. eleplwntium, Martini, I, 1, ~' A;-Dent. aprinum, Jb., 4, A;-D.8triatulum, lb., 5, B;-D. arcuatum, Gualt., X, G;-D. sexangulum. (2) Dent. dentalis, Rumpf., Mus., xli, 6;-D.fasciatum, Martini, Conch., T, 1,3, B;-D. rectum, Gualt., X, H, &c. (3) Dent. entalis, Martini, I, i, 1, 2, &c. ( 4) M. Savigny has made a family of this genus by the name of THELETllUSA!, which has been adopted by his successors. DORSIBRANCHIAT .tE. 455 an abundant yellowish liquid when touched. pairs of branchire( 1 ). It has thirteen AMPHINOME, Brug.(2) A· pairf of more or less complex, tufted or plumo se b ranc hI' re on each rmg o the body, and to each of the feet two f · I' f 1 • . . asctcu I o separate setre, anc two ctrrt; no Jaws to the proboscis. Th A . a1·e div' d by M. Savigny into e mphmomes CHLOEIA, Sav ., Where the . he. ad is furnished with five tentacula ' an d th e b ranchi·r e resemble a trtpmnate leaf. The Indian ocean produces one of them ' th e .9. mpm1 •n ome ch e - vellue, Brug.; Terebella .ftava' Gm .,• Pall ., M't sce 11 . VIII , 7- 11, very rema.r kable for its long bundles of Iem on-co1 o ure d setre, and the beautiful purple plumes of its bran c h't re. 1t s 1~ 0rm 1· s broad and depressed, and it has a vertical crest th And into the on e snout. PLEIONE, Sav.-AMPHINOME, Blainv., ~he1·e, with the same tentacula, the branchire are tufted. The Plewnes a1·e also from the Indian ocean ' and some of th em are very large(3). To these he adds the EuPHROSINE, Sav.(4) Whe.re the head has but a single tentaculum, and the tree-like branch1re are very complex and greatly developed. To this subgenus, Messrs Audouin and Edwards approximate the HIPPONOE, Which has no caruncle, and but a single bundle of setre and a single cirrus to each foot. ' Hip. Gaudichaudii, Ann. des Sc. Nat. t. XVIII, pl. vi. A species from Port Jackson. In the (1) Add .IJ.renicola clavata, Ranzani, dec. I, p. 6, pl. i, f. 1, should it prove to be a distinct species. (2) This genus has very properly been withdrawn by Brugieres, from the APunoDIT.IB of Pallas and the TEREBELL..iE of Gmelin. It forms the type of M. Savigny's family of the AMPUINOllt.lE, also adopted by his successors. (3) Terebellacarunwlata, Gm., .llmplt. car., Pall., Miscell., VIII, 12-13;-Ter. ro3trata, 14-18;-Ter. complanata, lb., 19-26;-Pleione alcyonia, Sav., Eg., Annel., II, f. 3. (4) Euphrosine laureata, Id. lb., f. 1;-E. mirto&a, Id., lb., 2. N.B. Thegenus AnxsTENIA, Sav., Eg., Annel., pl. ii, f. 4, shou1d also come near the Amphinomes; but it is only established on a mutilated specimen. |