144 THE CAT. [CHAP. v. 



(or upon the parts analogous in the female) as a delicate layer of 

 cutaneous muscular fibres. 



The ischlo-cavcrnosus is a small muscle arising from inside of the 

 ischium a little below its tuberosity and ending in a tendinous 

 expansion applied to a part hereafter to be described as the corpus 

 cavernosum (Fig. 115). 



The caudo-cavernosus is a slender muscle which passes backwards 

 from the under-surface of the root of the tail to the corpus caver- 

 nosum between Cowper's glands. 



Transrersus perencei. This is a small but very distinct muscle 

 which arises from the inner side of the ischium below its tuberosity. 

 It joins its fellow of the opposite sidel in front of the anal aperture, 

 being more or less united with the sphincter ani internus. 



The compressor iirethrce is a muscle which springs from the inner 

 side of the pubis, and divides into two portions, one passing above 

 and in front of, and the other below and behind, the urethra. 

 These portions end by meeting with corresponding divisions of the 

 muscle of the opposite side of the pelvis. It is very large in the 

 male, extending between the prostate and Cowper's glands. 



The ano-coccygcus arises (in the middle line) from beneath the 

 second and third caudal vertebrae, and passes downwards and back- 

 wards, expanding as it goes, to the upper part of the rectum. 



The recto-coccygeus arises from tne upper lateral part of the 

 rectum. It ascends, and, joining with its fellow of the opposite side, 

 passes upwards and backwards between the two ano-coccygeus 

 muscles to the under surfaces of the sixth and seventh caudal 

 vertebra. It is covered laterally by ilio-coccygeus and pubo- 

 coccygeus. 



The sphincter ani externus surrounds the root of the tail, the 

 anus, the anal pouches, and the external generative organs. It arises 

 from the dorsum of the tail at about the fifth caudal vertebra. The 

 anal pouches are two rounded sacs, each about as big as a pea, placed 

 one on each side of the rectum close to the anus. 



The sphincter ani internus is a mass of fibres arranged circularly 

 around the anus in front of the sphincter externus and more or less 

 united with it, especially with the fibres which constrict the anal 

 pouches. 



Thus just as the anterior end of the alimentary tube is surrounded 

 by a sphincter muscle the orbicularis oris so is its posterior 

 termination also surrounded by an analogous muscular constriction 

 the sphincter ani. 



This muscle is a more complete sphincter than its anterior 

 analogue, since it is not (as that is) interrupted by any median 

 notch. It is connected beneath with the transversus perensei muscles 

 at their median junction. Above, it is connected by a tendon with 

 the caudal vertebra) at the root of the tail. 



A retractor penis muscle passes from the ventral aspect of the 

 hinder end of the rectum, to the ventral surface of the penis towards 

 its distal end. 



