204 



ZOOLOGY. 



near the mouth. The umbrella is gradually withdrawn intct 

 the mouth, so that eventually only a crown of short tooth- 

 like projections surrounds the mouth. Finally the whole 

 umbrella is swallowed, the arms at the end of the body dis- 

 appearing, while the end of the intestine projects far out 

 from the body behind the mouth. By this time the PJtoro- 

 nis form is clearly indicated, the body being long and slen- 

 der and the mouth surrounded by a crown of short tentacles, 

 the end of the intestine being entirely withdrawn within the- 

 body. These changes are rapidly effected. The larva or 

 Ecltiurus is formed on the Annelid type. 



In Phascolosoma ccementarium (Quatrefages), the body is. 



much shorter than in P. Goul- 

 dii ; the worm lives in compara- 

 tively deep water (10 to 50 fath- 

 oms), in dead, deserted shells, 

 building out the aperture by a. 

 conical tube of sand. In Sipiin- 

 culus (Syrinx) the tentacles are 

 fringed or lobed. It does not. 

 occur in American waters. 



In Echiuriis the intestine ends 

 at the end of the body, and there 

 is a circle of bristles at tbe pos- 

 terior end, while Bonellia differs 

 in having an enormous proboscis, 

 and only a few bristles near the 

 head. In Bonellia virldix Eel. 

 of the Mediterranean (Fig. 141),. 

 the proboscis is deeply forked ; 

 the intestine is very long, convo- 

 luted, and into the cloaca empty 

 two excretory organs. The ovary 



the 



Fig. 141. Bonellia riridis ; 

 proboscis coiled several times. ;>, 



fore end of the proboscis ; ft, a', fur- . . . 



row in the proboscis ; j,i, digestive is a COl'd-llke Organ, wllich 111 the 



canal; m. mesenterial threads (only . ? / 1 i -i j 



shown on the anterior end of the di- posterior part 01 the body IS last- 



gestive canal); 17. organs of excre- , n , 



tiou c, cloaca ;' v, oviduo- -After Clicd to the intestine. 



Lacaze-Duthiers; from G CJltetodeniia nitidulum LoVell 



occurs in 20-40 fathoms off the coast of Europe and 

 Northern New England. The body is long, cylindrical, and 



