480 H. F. MOORE. [Vol. X. 



Each lamina contains a great blood sinus, expanded both 

 externally and internally, as shown in Fig. 9. These blood- 

 vessels have walls of their own, apparently structureless mem- 

 branes with very small, flat nuclei scattered sparsely on the 

 surface. 



These lamellar vessels are supplied by circular trunks in the 

 neighborhood of the septa, as shown in Fig. 10, which is a 

 tangential section. The circular trunks are given off from the 

 dorsal vessel, and may, at times, break up into a network 

 instead of remaining single; this vascular reticulum, however, 

 appears to be always confined to the immediate neighborhood 

 of the septum. 



The spaces lying between the laminae are lined, throughout, 

 by a granular layer containing numerous nuclei, each with a 

 nucleolus. The nuclei are especially abundant in contiguity 

 with the muscular and epithelial layers. 



The lining epithelium of this region consists of ciliated 

 columnar cells, the outlines of which are distinct in their free 

 moieties only; their bases become lost in the nucleated proto- 

 plasmic mass just mentioned. 



In somite XIV the epithelium loses its cilia and becomes 

 thrown into great ridges, shown in Fig. 8, e, which a little fur- 

 ther back abruptly terminate in backwardly-directed, valve-like 

 folds (Fig. 5, V). 



Claparede (7) has investigated the histology of the calcifer- 

 ous glands of Lumbricus terrestris, and my observations upon 

 Bimastos, whilst agreeing with his in the main, differ in certain 

 particulars. In reference to the blood supply of these glands, 

 and of the adjoining portion of the oesophagus, he states, 

 briefly, that longitudinal vessels run parallel to one another 

 and to the axis of the body, just beneath the epithelium, and 

 that they are connected, at intervals, by radiating vessels, with 

 a vascular net-work beneath the muscular layer. 



In the present species, as stated above, each longitudinal 

 vessel, and its connecting radiating vessels, are fused into a 

 vascular plate, extending from the epithelium to the muscular 

 layer, and extending the whole length of the septum between 

 the two adjacent follicles. In places, this vascular space may 



