192 CHORD ATA. 



ENTEROPNEUSTA. 



DOLICHOGLOSSUS (BALANOGLOSSUS) KOWALEVSKII. 



In the natural habitat, note the character of the bottom 

 where Dolichoglossus is found: Is the sand clean or is there an 

 admixture of organic material? Note the frail tube of sand 

 particles fastened together with mucus, and the numerous 

 "castings." The animal has a characteristic and unpleasant 

 odor. 



Note the division of the body into three general regions : (1) 

 A yellowish-white conical proboscis; (2) the collar, which is 

 brilliant orange-red, especially in males, with a white ring pos- 

 teriorly; and (3) the trunk, which is mainly orange-yellow, 

 shading to a greenish-yellow in the transparent posterior region, 

 which is often broken off when the animal is collected. 



The trunk may be roughly divided into the following regions, 

 which overlap: (a) An anterior branchial region, bearing on 

 each side not far from the dorsal median line a row of transverse 

 gill slits; (6) a genital region, bearing on each side of the body 

 an irregular and broken fold or ridge containing the reproductive 

 organs, which are gray in the female and yellow in the male; 

 (c) a posterior abdominal region, of much smaller diameter than 

 the rest of the body. 



The mouth is situated on the ventral side at the base of the 

 proboscis, and is concealed by the free anterior edge of the collar. 

 The animal is unable to close its mouth, and in burrowing a 

 continuous stream of sand passes through the alimentary canal, 

 forming the "castings" which are abundant in the natural 

 habitat of the animal. What must be the nature of its food? 



Burrowing is effected partly by muscular contractions of the 

 body-wall, but mainly through the power of the proboscis and 

 collar to become turgid. In burrowing and feeding, of what 

 use to the animal is the collar? 



Note the characteristic coiling of the genital region in this 

 species. The anterior end, including the branchial region, is 

 normally maintained in a vertical position. The posterior 

 end is also kept upright, and can be moved up and down in a 



