282 HAROLD HEATH. 



species studied by Mingazzini though there are some important 

 organs that have remained undescribed. The mouth (m) opens 

 into a gradually enlarging cavity, lined with a continuation of 

 the cuticle surrounding the body as far as the opening of the 

 ventral glands. At this point a large pouch-like diverticulum 

 (d) is developed chiefly on the dorsal side of the gut, and the 

 naked cells of its lining epithelium are relatively high and slender 

 and bear an excessively heavy coat of cilia at least two or three 

 times their own length. In his figures Mingazzini represents six 

 large retractors and a few smaller strands attaching to this point 



Fig. I. Larval gephyrean {Pelagosphaera). The stippling of the gut is merely 

 to differentiate the different divisions, d, dorsal ciliated diverticulum; g, glands 

 and duct, slightly displaced; m, mouth; p, ventrical non-ciliated pouch or pharynx; 

 s, stomach-intestine; v, ventral nerve cord leading to brain partially concealed 

 by pouch d. 



(though there is no sign of a pouch) and on the other hand 

 radiating outward to become united to the body wall. In the 

 present specimens the same is true. It appears probable there- 

 fore that this ciliated diverticulum may be everted and act as 

 a locomotor organ as Wilson^ has described in the case of Echiurus 



^ "Our North American Echiurids," Biol. Bull., Vol. i, 1900. 



