FEMALE GENITAL SYSTEM: EXTERNAL 39I 



abdominal cavity on each side of the genital tract. This plexus was described by 

 Bouvier (1892) for Hyperoddon rostra tus. In that species and in the Balaenoptera 

 foetuses dissected during this work the plexus in this region is extremely diffuse and 

 extends throughout the dorsal parietes of the abdominal cavity as far forward as the 

 level of the testis, where it receives contributions from the spermatic arteries and veins. 

 The arterial elements of the plexus are derived from all the surrounding arteries, and the 

 venous constituents similarly drain into all the venous channels of the region — that is 

 iliac, epigastric and pudic arteries and veins and the lumbar vein. In each of the foetuses 

 examined in the present work at least one large venous trunk was found running through 

 the mass of the inguinal venous plexus and draining into the iliac, lumbar or post-caval 

 veins (Figs. 1 k 2 , 12 k 2 ). The thickest part of this network lies immediately within the 

 pelvic bone. It is in very intimate relation with the two large lymph glands which 

 occupy a large part of the inguinal portion of the abdominal cavity (Figs. 1 m, 12 i). 

 One of these lies against the prostate and is compactly oval in outline, the other is more 

 diffuse and lies against the proximal part of the epigastric artery and vein. They are both 

 surrounded and embedded in the diffuse vascular mass. This mass of anastomosing 

 blood channels is not so dense nor so definite in outline as the thoracic and basicranial 

 " retia mirabilia ". It continues up the middle line of the body under the spinal column 

 in connection with the central lymph tract that occupies that area. 



Beauregard and Boulart found that the veins draining the testis are much larger than 

 the corresponding arteries and may be separated into two groups. One group comprises 

 all the veins of the testis and epididymis and is much the more important of the two. 

 This group lies at the posterior end of the testis above the cauda epididymis and the 

 origin of the vas deferens. It results from the union of three posteriorly situated plexuses 

 and two anterior plexuses. The latter are situated on the head of the epididymis and are 

 connected with the posterior ones by a large vein running along the testis dorsally. The 

 other group of spermatic veins contains only those coming from the lower part of the 

 epididymis. This group is situated outside the serous fold of the testis and epididymis. 



THE FEMALE GENITAL SYSTEM 



EXTERNAL 



In the female sex the external genitalia (Plate II, fig. 2; Plate III, fig. 1) are also 

 contained in a genital slit to which, since it constitutes the only common urinogenital 

 part of the system, the name "vulva" must be applied. The vulva in the female, 

 however, is of much greater extent than the genital slit or penis sac of the male, and 

 in the adult female at time of heat it gapes open so as to become oval in form, exposing 

 the structures within (Plate III, fig. 2). The vulva terminates posteriorly as a forked 

 groove, a triangular prominence, on which the anus is situated, lying between the 

 prongs of the fork. Mackintosh and Wheeler (1929, p. 324) have shown that the 

 distance between the centre of the vulva and the anus in the female is much less than 

 that between the penis sac and the anus in the male. It amounts to only 3 per cent 



