CONTEIBUTIONS TO THE ANATOMY OP THE HIEUDINEA. 467 



most superficial of these alone deserves the name cutaneous in 

 that sense of the term which I have adopted). 



1. The Deep Layer is divided into four longitudinal bands, 

 two of these are situated upon the dorsal surface — the larger 

 two. These arise from the latero-lateral and latero-dorsal vessels. 

 The other two bands are smaller. They are situated on the 

 ventral surface right and left of the ventral sinus ; they arise 

 from the latero-abdominal vessels. These capillary networks 

 are formed of botryoidal tissue (reseaux variquenx, Gratiolet). 

 They arise from the branches which are going to the skin. 



2. The Intermediate Layer. — The vessels composing this 

 network arise from branches coming directly from the lateral 

 system, and communicate on the other hand with the botryoidal 

 tissue. They form, by anastomosis among themselves, super- 

 posed networks which become finer and finer as they near the 

 surface, and finally passing into the subepidermic region give 

 rise to : 



3. The Superficial Layer. — The vessels forming which 

 are extremely fine and form an almost complete network; it is 

 these vessels which penetrate the epidermic layer.^ 



In the lateral regions small vessels, capillary at both extre- 

 mities, run in a vertical direction connecting the dorsal and 

 ventral superficial networks; they may be termed vertical 

 superficial branches (Gratiolet). 



These superficial networks are developed in a bilateral 

 manner, the communications between those of one side and 

 those of the other being few in number and excessively fine in 

 calibre. 



Ramifications of the Latero-abdominal Vessels. — 

 These latero-abdominal vessels, as described above, divide into 

 two diverging branches, an anterior and a posterior. 



The main trunk of the latero-abdominal furnishes a vessel 

 which ascends along the anterior limb of the " main lobe " of 

 the nephridium :- the vesicle of the nephridium receives its 

 vessels from its posterior bifurcation. 



1 Lankester, ' Quart. Journ. Micr. Sci.,' 1880, p. 303. 



2 Bourne, ' Quart. Jouru. Micr. Sci./ 1880, PI. XXIV. 



