16 CLASS ANNELIDA. 



Syphostoma, Otto, 



Which have at each articulation, superiorly, a bundle of fine 

 hairs, inferiorly, a simple seta, or bristle, and at the an- 

 terior extremity two parcels of strong and gilded bristles. 

 Under these bristles is the mouth, preceded by a sucker, sur- 

 rounded with many soft filaments, which may perhaps be 

 gills, and accompanied by two fleshy tentacula. The knotted 

 medullary cord is observable through the skin of the belly. 

 They live embedded in mud. — Siphostoma diplochaites, Oito; 

 Siph. uncinata, And. et Edw. Littoral, de la France, Annel. 

 pi. ix. fig. 1 , 



Hitherto has always been placed in this vicinity — 



Dentalium, 



Which have a shell like an elongated cone, arched, open at 

 the two ends, and which has been compared to an elephant's 

 tusk in miniature. But the recent observations of M. 

 Savigny, and especially of M. Deshayes, render this classifi- 

 cation very doubtful. See " Monographic du Genre Dentale, 

 Mem. de la Soc. d'Hist. Nat. de Paris," t. ii. p. 321. 



This animal does not appear to have any sensible articula- 

 tion, nor lateral seta ; but it has a membranous tube in front, 

 in the interior of which is a sort of foot, or fleshy and conical 

 operculum, which closes its orifice. On the base of this foot 

 is a small and flatted head, and gills in the form of plumes, 

 and visible in the nape. If the operculum remind us of the 

 foot of the vermetcB and siliquarice, which have been placed 

 among the mollusca, the gills strongly remind us of those of 

 the Amphitritse and Terebellae. Ulterior observations on their 

 anatomy, and principally on their nervous and vascular sys- 

 tem, will resolve this problem. 



Some of these have the shell angular, or longitudinally 

 striated. — Dent. Elephantinum, Martini ; I. i. 5. A. ; D. 



