THE LYMPHATIC SYSTEM. 255 



forms the boundary between the belly and thigh; on the dorsal 

 surface it is more posterior, and is attached to the dorsal surface of 

 the muscles of the thigh at some little distance from the trunk. It 

 completely surrounds the root of the hinder limb. It has attached 

 to it the ventral, dorsal, and iliac septa, together with the septa 

 of the thigh. 



b. The lymph-sacs. 



(1) The dorsal lymph-sac (Saccu.* cranio-dorsali*), (Figs. 169 and 

 171 i). This is a large lymph-sac, extending from the tip of the 

 snout to the tip of the urostyle ; it is bounded in front by the 

 attachment of the skin to the premaxillary bones ; the line of 

 attachment is continued, on either side, along the inner border of 

 the external nares, then forms a pouch towards the jaw and in front 

 of the eye, and runs backwards along the upper border of the orbit, 

 where it is attached to the upper eyelid, to the inner border of 

 the tympanic membrane. In this course the skin is firmly attached 

 to the underlying parts. The lateral boundary of the lymph-sac, 

 behind this point, is formed by the dorsal septum, which separates 

 it from the lateral lymph-sac. 



(2) The ventral lymph-sac (Sa<-<:-<'* aMo/ai/ia/i*), (Figs. 170,171 2) 

 is triangular in form, with the base forwards at the breast, and the 

 apex behind at the pelvic symphysis ; it occupies the space between 

 the skin below and the belly muscles and part of the M. pectorali* 

 above. It is bounded anteriorly by the pectoral septum (/>) and 

 laterally by the ventral septa (a). 



(3) The lateral lymph-sac (Saccv* lateral^}, (Figs. 169, 170, and 

 171 .;) exists on either side; below, the sac is bounded by the 

 ventral septum (a), above by the dorsal septum ('/), anteriorly by the 

 maxillary septum (m), and posteriorly by the inguinal septum (/) and 

 the wall of the iliac lymph-sac. 



(4) The submaxillary lymph-sac (Saccus snlmaxillari*}, (Figs. 



170 and 1714) is a space between the M. wlmaxiUari* and the 

 skin ; the sac is bounded behind by the maxillary septum, which 

 separates it from the pectoral lymph-sac, and more laterally from 

 the lateral lymph-sac. In front and at the sides the skin is firmly 

 attached to the margin of the mandible. 



(5) The pectoral lymph-sac (Saccv* tltoracicv*}, (Figs. 1 70 and 



171 5) lies between the submaxillary and ventral lymph-sacs. The 



