8 ART. 11. — A. IZÜKA : OBSERVATIONS OX THE 



Peristomium. — The peristomium or the first segment shows 

 much longitudinal folding. On each side it is provided with 

 four tentacular cirri, two dorsal and two ventral. The anterior 

 ventral cirrus is the shortest, and the posterior dorsal the longest. 

 The latter, when laid down backwards, reaches to about the 

 the middle of the fourth segment. Each cirrus consists of a 

 basal, more or less pigmented, section and of a colorless distal 

 section pointed at the free end. 



Proboscis. — PL II., figs. 10 and 11, show respectively the 

 dorsal and the ventral views of the proboscis in its protruded 

 state. It is furnished with a pair of strong chitinous jaws and 

 a number of soft papillae. The blackish brown but translucent 

 jaws are slightly curved and their inner concave edge shows 7-9 

 teeth. Structurally, the jaws consist of a peripheral colored layer 

 and an inner colorless mass. The latter is concentrically laminated 

 and incloses two longitudinally running canals, which open ex- 

 ternally on the points of the first and the second teeth. The 

 canals contain a substance which in its staining capacity resembles 

 the secretion of the " Spinndrüsen," a gland found in the dorsal 

 ramus of certain parapodia. In the fully protruded state of the 

 proboscis the points of the jaws are apart ; these close and become 

 crossed as it is withdrawn. They serve not only for capturing 

 prey but also for burrowing into the bottom-ground. 



The surface of the proboscis, when protruded, is divided by 

 a ring-groove into a posterior and an anterior ring, both of which 

 are again subdivided into a number of small areas by grooves 

 which run in the main longitudinally. The posterior ring is 

 entirely destitute of papillae, these being confined to the anterior 

 ring. This latter ring (PI. TI. fig. 10), seen on the dorsal side, 



