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, 
he. ). The longitudinal vessels may, however, 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 Collar 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 by the formation of a longitudinal fold 
of the limiting membrane of the epidermis, a median longitudinal 
subepidermic vessel (fig. 18, slv.) may in some cases be formed 
opposite 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 perihsemal 
spaces and the collar cord. These laterally pass upwards in the 
