40 Prof. M'Intosh's Notes from the 



project from their inner edges, and the duct lies to the 

 v< utral or inner edge of the tori and the bristles. When the 

 tube has about 18 cells in its wall (and is therefore small) 

 the glandular or dorso-lateral appendix, cm., is fully twice 

 its diameter, and soon the tube vanishes, leaving only the 

 thin glandular belt within the body-wall. This dorso-lateral 

 appendix appears to be somewhat akin to the multinucleated 

 coelomic bodies described by Prof. Caullery * in Eunice 

 harassii, Aud. & Ed. As already mentioned, the ducts from 

 the anterior end show flask-shaped brown granular glands, 

 but the single duct formed by their union is quite pale. 



Toward the termination of the thoracio glands, and behind 

 thern, the coelomic cavity contains vessels and ehloragogenous 

 tissue covered with opaque granular masses, often enveloped 

 in the ehloragogenous sheaths. These continue for some 

 distance backward and by-aud-by disappear. 



Whilst the thoracic glands are still of moderate size — that 

 is, toward their posterior third, — it is noticeable that they 

 are bounded externally by a firm layer of the body-wali 

 ending interiorly in a free process, which in transverse 

 section is clavate (PI. V. fig. 28, p.). This layer, ab., has 

 rather regularly arranged fibres at right angles to the axis 

 of the body, which stain like the muscles in their neigh- 

 bourhood, and do not resemble the hypodermic nucleated 

 cells. It has externally the pad or process bearing the 

 hooks, and it terminates ventrally, rather past the middle of 

 the section of the thoracic gland with its appendix, in the 

 free process, the ventral end being pale. The narrow bar, 

 however, proceeding forward, soon enlarges into a thicker 

 layer of prism-like cells with the nuclei at their free surface, 

 thus giving the aspect of a series of punctures at the en- 

 larged outer ends, for the cells, ce., are clavate and minutely 

 granular (PI. V. fig. 29). This peculiar cellular layer runs 

 upward on the external border of the branchial stalk, the 

 inner layer, continuous with the dorsal hypoderm, pre- 

 senting quite a different structure, and the nuclei are 

 within their superficial ends (PI. V. fig. 29). The function 

 of this special cellular development would seem to be in 

 connection with the well-developed hook-pads of the region 

 rather than with the thoracic glands, probably acting as an 

 elastic cushion. The muscular fibres seen in PI. V. fig. 28, m., 

 are those which move the hook-pad, whilst that structure 

 itself is largely composed of the modified hypodermic cells 

 just described. Hence the appearances of the parts vary 



* Compt. rend. Soc. Biol. t. lxxviii. p. 593 (J 915) 



