THE PHYLUM CHORDATA 



61 



self tightly with water through the collar pore, comes 

 to fit itself rigidly against the sides of the hole and 

 to act as a fulcrum for the further operations of 

 the proboscis. Thus progress is accelerated. Sand 

 is quickly loosened and taken up by the scoop-like 

 mouth which is situated between the base of the 

 proboscis and the ventral part of the collar. If 



rob 



cilv 



FIG. 33. Bd- 

 anoglossus. br, 

 branchial region; 

 co, collar; gen, 

 genital ridges; 

 hep, hepatic prom- 

 inences formed 

 by hepatic (liver) 

 caeca; pr, probos- 

 cis. (From Lull 

 after Spengel.) 



ventv 



FIG. M.Balanoglossus. Diagrammatic sagittal section 

 of anterior end. card, s, cardiac sac; div\ diverticulum, (sup- 

 posed notochord); dors, n, dorsal nerve strand; dors, fin, dorsal 

 sinus; dors, ves, dorsal vessel; mo, mouth; prob, proboscis; prob. 

 po, proboscis pore; prob. skel, proboscis skeleton; vent, n, ven- 

 tral nerve strand; vent, v, ventral vessel. (From Parker and 

 Hasvvell, after Spengel.) 



we may be pardoned a somewhat homely analogy, we may com- 

 pare the collar of Balanoglossus to a too-large collar of a man and 



