BY JAS. P. HILL. 37 



vessels of the collar, formed by folds of the outer limiting mem- 

 brane of the peripharyngeal space. 



The circular vessels stand in direct connection as in the 

 described species with the capillary net in the outer limiting 

 membrane of the peripharyngeal space, and also anterior to the 

 line of termination of the latter with the capillary vessels below 

 the epithelium immediately surrounding the mouth aperture. 



The ventral longitudinal vessels generally consist in this species 

 of two distinct folds which may be secondarily branched (fig. 18, 

 Ivc. ). The longitudinal \essels may, hoAvever, be represented by 

 a single simple or much branched fold, or of three or four distinct 

 folds. 



As in the described species the ventral longitudinal vessel folds 

 open at their posterior ends into a lacuna in the collar-trunk 

 septum, into which the circular vessel passing in the septum 

 immediately below the circular nerve ring opens laterally, and 

 from which the ventral longitudinal vessel of the trunk takes its 

 origin. 



Capillary System of CoUar is related essentially as in the 

 described species. On the dorsal side, the vessels in the limiting- 

 membranes of the "roots" placing the outer and inner capillary 

 nets in connection are strongly developed (fig. 15). Yentrally, in 

 the hind half of the collar l)y the formation of a longitudinal fold 

 of the limiting membrane of the epidermis, a median longitudinal 

 subepidermic vessel (fig. 18, dv.) may in some cases be formed 

 (jpposite the ventral longitudinal plexus. Posteriorly, the former 

 fuses with one of the folds of the latter, and the capillary net of 

 the inner collar wall is thus brought on the ventral side into 

 direct connection with that of the outer. In some individuals, 

 however, the ventral mesentery may be entirely absent, and no 

 such connection established. 



The capillary net surrounding the dorsal cord is in this species 

 strongly developed, and especially on its dorsal side (figs. 15 and 

 17) well-marked vessels (fig. 17) pass off, from the dorsal side of 

 the dorsal vessel, in the limiting membrane between the periha?mal 

 spaces and the collar cord. These laterally pass upwards in the 



