290 MESSRS. B. C. A. WIXDLE AXD F. G. PARSOXS OX [Nov. 3, 



Perineal and Caudal Regions. 



SpJdncter ani. — This muscle has the human attachments in 

 male animals, but in females it is continuous with the sphincter 

 vaginse, forming the sphincter cloaca?. This is certainly the case 

 in the Mare, the Sheep, the Chevrotain, and the Hyrax. 



Transversus perinei. — Thompson (XXXVI.) says that this 

 muscle is absent in Ungulates ; it is described, however, by Kinberg 

 in the Chevrotain (X.) and by Chauveau in the Horse and Bull 

 (II.) We have seen it in the Sheep, but we agree with Thompson 

 that it is not well marked. 



Bulho-cavernosus. — As the bulb is a bifid structure in Ungulates, 

 the two halves of the muscle are separated by a wide raphe and do 

 not unite in the middle line. 



Ischio-cavernosihs. — This is always well developed and rises from 

 the inner side of the tuber ischii, it then turns forward, wrapping 

 round the crus penis or clitoridis. Thompson gives a good illus- 

 tration of it in the Camel (XXX YI.). 



The Compressor iirethrcje surrounds the membranous portion of 

 the urethra and consists, as in Man, of an upper and lower bundle ; 

 it differs from the human muscle in not being definitely attached 

 to the pelvic wall. 



Levator ani. — Thompson (XXXYI.) has shown that the levator 

 ani of Man is a compound muscle consisting of two modified tail- 

 muscles — the ilio- and pubo-coccygeus supplied by the saci-al plexus, 

 and an ischio-anal muscle which is a derivative of the sphincter 

 cloacae and, like that muscle, supplied by the pudic nerve. He 

 points out that in the Ungulates only the ischio-anal muscle is 

 present, and in this we can agree with him, though Gratiolet (III.) 

 describes an ilio-coccygeias in the Hippopotamus and says that it is 

 inserted into the anterior three caudal transverse processes. 



Ischio-coccygetis (Coccygeus). — This is well developed in the 

 Artiodactyla, and rises from the pelvic surface of the ischial spine 

 or the region where that structure would be, as well as from the 

 sacro-sciatic ligament. It is inserted into the anterior caudal 

 transverse processes. Lesbres (V.) points out that in the Equidse 

 it is not well developed, and Chauveau (II.) agrees with this. Joly 

 and Lavocat (XII.) deny its presence in the Giraffe, but Murie 

 definitely found it in that animal. It is supplied by the sacral 

 plexus. 



Sacro-coccygeus superior (Levator caudte ; Extensor caudte). — This 

 rises from the sacral spines, and is inserted into the dorsal surfaces 

 of the caudal vertebrfe by a series of separate tendons. In those 

 Ungulates in which the tail is well developed, a division into 

 external and internal layers may be made out as in other mammals. 



Sacro-coccygeus lateralis is the continuation backwards of the 

 semispinalis layer of the erector spinse. 



Sacro-coccygeus inferior (Depressor caudse ; Curvator coccygis). — 

 As Lesbres points out (Y.), there are external and internal parts of 

 this muscle, the latter being slightly developed and reaching only 



