GASTEROPODA PBCTINIBRANCHIATA. 77 



locomotion, is deprived of afoot, properly so called; but the part 

 which in ordinary Gasteropoda forms the tail, is here turned under 

 it, and extends to beyond the head, where its extremity becomes 

 inllatrd and furnished with a thin operculum; when the animal 

 withdraws into its shell, it is this mass which closes the entrance; 

 it is som. -times seen with various appendages, and in certain species, 

 the opcrculum is spiny. The head of the animal is obtuse, and has 

 two m.ideiate tent-.icul.i, on the external sides of which, at the base, 

 arc th" eyes. The mouth is a vertical orifice, beneath which is a 

 filament "on -a"h .side, that his all the appearance of a tentaculum, 

 but belonging in reality to the foot. The branchiae form but a single 

 range along the left side of the roof of the branchial cavity. The 

 right side is occupied by the rectum and the spermatic canal, which 

 transmits the ova. There is no penis, the animal fecundating 



The species are numerous, but not very distinct. Linnaeus 

 left them among the Serpuhe*. 



Th- Vermili&i also K-ft by M. de Lamarck near the Serpula?, are 

 similar to the Verraetif. 



MAGILUS, Montf., 



i Magili have a longitudinally carinated tube, which is at first 

 regularly spiral, and then extends itself in a line more or less straight; 

 although th.- animal is unknown, it is highly probable that it should 

 be placed near the Ver.neti J. The 



SlLIQUARIA, Bl'Ug. 



I! emblea Vermetus in the head, the position of the operculum, and 

 in the tubular ;md ii regular shell; but there is a fissure on the whole 



h of this shell which follows its contour, and which corresponds 

 to a .similar (left in that part of the mantle which covers the branchial 

 cavity. Along the whole side of this cleft is a branchial comb, com- 

 posed of numerous, loose and tabular-like lamellae. Linnaeus left 

 them with the Serpula-, and till very lately they were considered as 



iging to the class of the Annelidesg. 



* Serpulu lumbricalis, L., Adans., Senegal, XI, 1, and several new species. 

 f Strpn><ifri<jtirfr,i, (im., H.rn., Mas., pi. xviii, t. 14. 



' mtf. II, pi. 4:i, and Guettard, Me*ra., Ill, pi. Uxi, f. 6. 

 ..'"/.I anyuina, L.; Serpulu muricata, lion)., Mu-., XVIII, 16. 



the Siliquarix and the Vcrmilie as neighbours 



of Hi M. ilt- Mliiiuvillf h:i< approximntfJ them to tin- Ymm'ti ; M . An- 



ii.--.iiu has lately obscn'cd and describnl the uniiiiuJ, and to him do we owe \\i 

 stated above. 



