652 



ANATOMY OF VERTEBRATES. 



507 



In the Guinea-pig ( Cavia cobaya), the 6 os penis ' is_a_flat 

 and slightly curved bone imbedded in the upper part, and 

 reaching as far as the extremity of the glans above the canalj>f 

 the urethra. Behind and below the termination of the urethral 

 canal is a wide pouch, in the bottom of which are lodged two 

 horny styles. This pouch, during erection, is everted, so that 

 the horns protrude externally. Two tendons are connected with 

 the bottom of this pouch, which run along the penis inferiorly, 

 and come from a thin layer of muscular fibres, derived from the 

 erectores : they invert the pouch and draw it back again within 

 the glans. The surface of the glans is beset with corneous scales. 

 This singular armature of the intromittent organ 

 is maximised in the spotted Cavy (Coelogenys 

 subfuscus), of which, fig. 507 shows the glans 

 beset with short spines, the long terminal horny 

 spikes, and the lateral horny plates, with marginal 

 retroverted serrations. 



In Capromys I found a larg'e adipose append- 

 age attached to the epididymis. The ducts of 

 the seminal, vesicular and prostatic glands termi- 

 nate by distinct orifices ; the fossa receiving those 

 of the right side being divided by the verumon- 

 tanum from the left one. The protometra is 

 reduced to a small cul-de-sac behind the neck of 

 the bladder ; it seems like a blind backward con- 

 tinuation of the urethra separated by a transverse 

 ridge from the orifice of the bladder. The vesi- 

 cular glands present a white and glistening ex- 

 terior ; they are of an elongated form, with thin 

 parietes, and send off, on one side principally, from fifteen to 

 twenty obtuse caecal processes. The prostate gland consists of 

 four principal masses or lobes, each composed of a number of 

 flattened tubular caeca, with thin and easily lacerable parietes, 

 compacted together by cellular tissue. The muscular part of the 

 urethra is closely embraced by a thick stratum of muscular fibres, 

 diverging in a double oblique or penniform manner from a middle 

 longitudinal inferior raphe : the ' acceleratores uringe ' have the 

 usual relations to a large bulb of the urethra : the crura penis 

 are embraced by short but strong { erectores ; ' the ' levatores ' 

 muscles, or ( compressores venae dorsalis,' terminate in a single 

 tendon, passing along the dorsum penis, to be inserted into an 

 elongated flattened ossicle in the glans, which, in this genus, is 



1 xx. vol. iv. p. 75, Nos. 2495, 2496. 



Glans penis of the 

 spotted Cavy. 1 



