266 J. H. ASHWOETH. 



ceedingly abundant^ and here, too, on each side are a few large 

 unipolar cells with prominent nuclei. There seems to be a 

 definite nerve-tract arising from this mass of cells and passing 

 into the connective. The fibres of the connective appear to 

 be derived almost entirely from the anterior and middle 

 portions of the brain, only a very small proportion being 

 derived from the posterior lobe. In the posterior lobe there 

 is also a number of larger cells, but the fibrous and cellular 

 elements are in almost the same proportion as in younger 

 specimens. 



The CRsophageal Connectives. 



The connectives arise from the brain, slightly anterior to 

 the middle of its length. They run just beneath the epi- 

 dermis, and at first fall nearly vertically downwards near the 

 middle line, then diverge sharply, pass round the mouth, and 

 unite just anterior to the level of the second chtetigerous 

 annulus to form the nerve-cord. The course of the connec- 

 tives is marked externally by the metastomial grooves, which 

 are well seen only in comparatively few specimens. 



The connective of each side gives off nerves to at least two, 

 and sometimes three, annuli, through which it passes, and also 

 a nei've through which it runs along the sides of the mouth 

 to theeversible part of the pharynx. The former nerves are 

 situated just beneath the epidermis; the latter nerve, which 

 also supplies the upper lip, may be traced by the aid of its 

 distinct sheath for some distance along the dorso-lateral 

 region of the pharynx between the epithelial and muscular 

 layers, and is probably in connection with the stomatogastric 

 system. 



The connectives are composed chiefly of fibrous matter, 

 but there is a thin coating of cells on the external face, and 

 at the point of union of the two connectives there are several 

 larger nerve-cells. The connective is enclosed in a sheath of 

 neurilemma, which is better developed in old specimens, and 

 in the latter serids ingrowths which partially subdivide the 

 connective into two or three. 



