228 



BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY, 



Fig. 42. — Paranemertes californlca. 

 Central stylets and bases from three 

 individuals, showing variation in size 

 and shape. 



even diameter throughout (1*1. 11, tig. 75; Text-tigs. 41, 42) ; stylet 

 moderately slender, about half as long as basis, or sometimes a httle 



more than half as long. Usually two 

 or three accessory stylets in each of 

 the four or six pouches, all of which, 

 as well as the central stylet, show a 

 ])eculiar darker or more opaque por- 

 tion about the head (PI. 11, fig. 75; 

 Text-fig. 48). 



Length of basis aljout 0.36 mm. ; 

 average width 0.1 mm. ; length of 

 stylets 0.17-0.2 mm. Usually 10 

 prol)oscidial nerves, occasionally 11 

 or 12. 



Ocelli. — Two very small ocelli, 

 occasionally fragmented into two 

 groups of minute granules, are situ- 

 ated near the tip of snout. They lie 

 deep in the tissues of the head and are difficult to see in the living 

 worm, lieing visually distinguished readily only after the specimen 

 has been cleared in some suitable medium. 



Cerebral sense organs extremely small, measuring scarcely more 

 than one tenth the diameter of head in same 

 region ; situated Avell in front of brain, and con- 

 nected with exterior on latero-ventral margins of 

 head near tip of snout. 



Cephalic glands voluminous, composing the 

 greater ])ortion of the tissues of head in front of 

 brain, and being intersjjcrsed with connective 

 tissue and muscle libers. 



Submvscidar glaiids sj^arsely scattered in eso- 

 phageal region. 



Miiscidar system. — A peculiar secondary longi- 

 tudinal muscular layer arises in the head quite 

 independently of main longitudinal muscles ; it 

 increases greatly in size back of brain, but remains 

 separated from the musculature of the body walls 

 by a thick layer of parenchyma. Back of brain 

 this secondary muscular layer (Text-fig. G) be- 

 comes thicker than longitudinal layer of body Avails, and its fibers 



Fig. io.~ Parane- 

 mertes califor- 

 nica. Accessory 

 stylets, highly 

 magnified, show- 

 the peculiar stri- 

 ated basal jjor- 

 tion of each. 



