162 



ZOOLOGY. 



near the mouth. The umbrella is gradually withdrawn into 

 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 Phoro- 

 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 the end of the intestine being entirely withdrawn within the 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 of 

 Echiurus 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 Sipun- 

 culus (Syrinx) the tentacles are 

 fringed or lobed. It does not 

 occur in American waters. 



In Echiurus the intestine ends 

 at the end of the body, and there 

 is a circle of bristles at the pos- 

 terior end, while Bonellia differs 

 in having an enormous proboscis, 

 and only a few bristles near the 

 head. In Bonellia viridis Kol. 

 of the Mediterranean (Fig. Ill), 

 the proboscis is deeply forked ; 

 the intestine is very long, convo- 

 the luted, and into the cloaca empty 

 two excretory organs. The ovary 

 row in 'the probo'scisTC*' digestive is a cord-like organ, which in the 



canal : m, mesenterial threads (only . * 1 i. T 4 j. 



shown on the anterior end of the df- posterior part OI the DOCly IS last- 



^7'VSi ; ^r r lv a K f -!I?t r e e ; ened to the intestine. 



Lacaze-Dcthiers ; from Gegenbaur. QhCBtoderma nitidullim Loven 



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

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



Fig. 111. BoneUia viridis; 

 proboscis coiled several times, p, 

 lore end of the proboscis ; , &, fur- 



