THE PHYLUM CHORDATA 



61 



,ye«) 



Fig. 33.— Bal- 

 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.) 



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 



hnb.eh&l 



"ciors-v 



Fig. 34. — Balanoglossus. Diagrammatic sagittal section 

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

 posed notoohord); dors, n, dorsal nerve strand; dors, sin, dorsal 

 sinus; dors, ves, dorsal vessel; mo, mouth; proh, proboscis; -proh. 

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

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

 Haswell, 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 



