132 ANNELIDES. 



tube bent towards the head, which doubtless affords an issue to the 

 faeces. I have found a muscular gizzard in them*. 



Such is the species found along the coast of France, the Sa- 

 bella alveolata, Gm. ; Tubipora arenosa, L. ; Ed. XII, Coral., 

 XXXVI. Its tubes, united in one compact mass, have their 

 orifices regularly arranged like the cells of a honey-comb f. 



Another, the 



Amph. ostrearia, Cuv., establishes its tubes on the shells of 

 Oysters, and it is said greatly hinders their propagation. 



It is to this order I suspect that we must refer the 



SYPHOSTOMA, Olto, 



Where, on the superior part of each articulation, is inserted a fasci- 

 culus of fine setae, a*id on the inferior a simple seta, and on the ante- 

 rior extremity two fasciculi of strong golden coloured setae. Under 

 these setaceous appendages is the mouth, preceded by a sucker sur- 

 rounded by numerous soft filaments, which may veiy possibly be 

 branchiae, and accompanied by two fleshy tentacula. The knotted 

 medullary cord is seen through the skin. They live buried in mud J. 

 Hitherto, the genus 



DENTALIUM, Lin. 9 



Has always been placed in this vicinity. The shell is an elongated, 

 arcuated cone, open at both ends, and has been compared to the tusk 

 of an elephant in miniature. The recent observations of M. Savigny, 

 and those of M. Deshayes especially , have, however, rendered this 

 classification extremely doubtful. 



The animal of the Dentalia, has neither any sensible articulation, 

 or lateral setae, but is furnished anteriorly with a membranous 

 tube, inside of which is a sort of foot, or fleshy and conical opercu- 

 lum, which closes its orifice. On the base of this foot is a small 

 flattened head, and plumose branchiae are observed on the nape. If 

 the operculum recall to our minds the foot of the Vermeti and Sili- 

 quariae, which have been placed among the Mollusca, the branchiae 

 strongly remind us of those of the Amphitrites and Terebellae. 

 Ulterior observations upon their anatomy, and principally upon that 

 of their nervous and vascular system, will resolve this problem. 



* The SABELLARI^E, Lam. ; the HERMELL.E, Savigny. 



f This is perhaps the place for the Amphitrite plumosa of Fab., Faun. Groenl., 

 p. 288, and Mull., Zool. Dan., xc ; but their descriptions are so obscure, and agree 

 so little with each other, that I dare not attempt to assign it. It forms the genus 

 PHERUSA, Blainville. 



J Siphostoma diplochaito$, Otto ; Siph. vncinata, Aud. and Edw., Litt., de la Fr., 

 Annel., pi. ix, f. 1. 



Monograph of the genus DENTAHUM, Mem. de la Soc. d'Hist. Nat. de Paris, 

 t. II, p. 321. 



