650 ANATOMY OF VERTEBRATES. 



its communication with the urethra. The pro tome tra, 1 d, has thin 

 walls, except at its terminal neck, where it seems thickened by the 

 adhesion of prostatic follicles, opening by distinct ducts into the 

 urethra. The Cowperian glands lie at the sides of the muscular 

 tract of the urethra, and open into it. The penis is short, consisting 

 chiefly of a pyramidal pointed glans ; it is exposed at b, in its 

 prepuce, which opens into the subanal fossa, a, into which the 

 preputial or ano-preputial glands, k, I, exude their firm sebaceous 

 secretion. The ? erectores penis ' arise from both pubis and 

 ischium, and are inserted chiefly into the outer side of the i crura 

 corporis cavernosi: ' the ' levator penis ' arises from the symphysis 

 pubis, and is inserted into the glans by a small tendon, passing 

 along the dorsum penis, over the convex bend, which it straightens 

 when the penis is extended in erection. The Rabbit differs from 

 the Hare chiefly in the larger relative size of the protometral 

 vesicle, which also more commonly shows a bilobation of the 

 base : its terminal orifice, in the urethra, is transverse and cre- 

 scentic * as if bent round the swellings of the verumontanum.' 2 

 Lagomys resembles Lepus in its male generative organs. 



The vesicular glands are present, but small, in the Sciurine 

 family. In the grey Squirrel they are slender, somewhat elon- 

 gated bodies, bent upon the base of the prostate, through the 

 substance of which their comparatively long ducts pass, together 

 with the vasa deferentia. The prostate is a relatively large 

 elongated compact body, loosely attached to the posterior part 

 of the neck of the bladder and muscular part of the urethra. 

 Cowper's glands are also relatively of large size ; they are situated 

 at the sides of the rectum, of a rounded conical form with the 

 base bent forward upon the apex, from which a long, thick duct, 

 with glandular parietes, is continued into the bulb of the urethra. 

 The diminutive size of the so-called ' vesiculae seminales ' is not 

 compensated by a dilatation of the vasa deferentia, as might have 

 been expected had their office been to serve as a reservoir for the 

 secretion of the testes, but by the magnitude of the other glands, 

 viz. the prostate and Cowper's, the admitted function of which is 

 to add some accessory fluids to the semen ; and the Squirrels do 

 not differ in the mode or duration of the act of copulation from 

 other Rodents in which the vesicular glands are largely developed. 



In the Porcupine (Hystrix cristata) the ' tunica vaginalis testis' 

 adheres to the scrotum and abdominal ring by so much and so 

 lax areolar tissue that its inversion with return of the testis to 



1 ccxxxvi, vol. ii. p. 167 (note). ' Uterus maseulinus,' ccxxxvm". passim. 'Cor- 

 pusculum Weberianum,' ' Vesicula prostatica,' 'Sinus prostaticus,' ccxxxix". p. 1415. 



2 ccxxxix". p. 1419. 



