OLIGOBRACHIA DOGIELI 



157 



its base. The tentacles, whose number varies from 6 to 9, are attached in a 

 single row, horseshoe-wise, whose ends turn inwards on the ventral side and 

 almost close up into a full ring. The tentacles are 6-10 times longer than the 

 anterior section of the body, and each of them bears on its inner side two rows 

 of very delicate pinnules, 0-75 mm long, so arranged that they alternate with 

 one another (Fig. 90). Microscopic study of living tentacles clearly reveals 

 afferent and efferent blood capillaries running together at the tip of each 

 pinnule, while groups of granular gland cells are visible in the tentacles 

 themselves. 



Fig. 90. Oligobrachia dogieli: Part of a tentacle in vivo, 

 eg - gland cells; pi - pinnules. (After Ivanov, 1957a.) 



On the ventral surface of the cylindrical mesosoma runs a narrow median 

 furrow (Fig. 89л(, В), and the delicate yellowish keels of the bridle, lying on 

 cutaneous folds, are continuous on the ventral side, but broken dorsally, 

 where their ends become thinner. 



The front part of the metasoma, or trunk, has a well-marked ventral 

 groove, which is bounded on each side by a wide ridge, through whose 

 integument may be seen numerous pyriform glands, crowded together 



