TUUICOL/E. 3S1 



tacular cirri upon the head (Capitifa'anchiata), of which one or 

 more may bear an operculum at its apex to clo.M- (lit- tube (tig. 

 308). The para podia, are short, and are never used in swimming; 

 the notopodia. usually carry hair-like seta 1 ; the neuropodia are trans- 

 verse ridges with hooked seta j or plates. Eyes are very frequently 

 absent : in other cases thev are present in pairs upon the head or 011 

 the terminal segment, sometimes even on the branchial tentacles; 

 in the Litter case they are very numerous. The body is often 

 divided into two (thorax and abdomen) or three regions, the seg- 

 ments of which are distinguished by their unequal size. The 

 Tufiicolt.r live in more or less tirm tubes which they construct for 

 themselves, and feed on vegetable matter which they procure bv 

 means of their tentacular apparatus. In the construction of their 

 tubes the animals are assisted in various ways by the long tentacles 

 or branchial filaments of the head ; thus, for example, the Sabellidce 

 are said to accumulate fine ooze at the funnel-shaped base of the 

 branchial apparatus by means of the cilia of their tentacles, to mix 

 it with a cement secreted by large glands, and then to transfer it to 

 the edge of the tube; while the Terebellidce procure the grains of sand 

 for the construction of their tubes by their long and very extensible 

 tentacles. There are also boring Annelids, which pierce limestone 

 and mussel shells, like the horny Molluscs ; ?.</., tialwlla saxicola, etc. 

 The development is simplest when the mother possesses a kind of 

 brood-pouch for the development of the young, e.y., Xj>irurl>in xpirUltun 

 Pag., the eggs and larva? of "vhich remain within a dilatation of the 

 opercular stalk until the young animals are able to construct a tube 

 for themselves. The free-swimming larva? of most Tubicola 1 , on 

 assuming the form of the worm, lose the ciliary apparatus, while 

 tentacles and parapodia make their appearance. In this condition 

 and sometimes surrounded by delicate membranes, they swim about 

 for some time longer, and, having lost their eyes and auditory vesicles, 

 gradually assume the structure and mode of life of the sexual animal 

 (Terebella). 







Kam. Saccocirridae. With two 'tentacles on the pvfestomium. two eyes 

 mi. I the same number of ciliated pits. A single row of retractile parapodia, 

 furnished with simple seta}, on either side of the segments of the body. Snrro- 

 cirrus pajnlloccrcus P>obr.. Black Sea and Mediterranean (Marseilles). 



Fam. Arenicolidae. I'm^tumiiim small and without tentacles. The pro- 

 boM'i-; is beset with papilla?. There are branched gills, on the median and 

 posterior segments. The animals burrow in sand. Ari-niculn niiirhin Lin. 

 (A. />ixt'i<f<>niiii Lam.), North Sea and Mediterranean. 



Fam. Spionidae (Sjiim/cn"'). The small pnvstomium sometimes with tenfacu- 



