1880.] VARIATION IN EQUUS ASINUS. 5 



masses of laminae of epithelial debris. The dilatatores naris vary in 

 their arrangement in relation to this pouch ; thus, ordinarily a con- 

 tinuous series of fibres extends to it from above, behind, and below, 

 being the superior and inferior dilators. But we have seen excessive 

 development of the band against the cul-de-sac of the pouch and 

 deficiency of the other parts of the series. The posterior extremity 

 of retractor labii superioris has sometimes a muscular addendum 

 connecting it with the zygomatic ridge. 



Mylr.hyoideus varies somewhat in being divided generally at its 

 anterior part into two distinct planes. 



Geniohyoideus sometimes sends a small distinct band to genioglossus 

 at about the centre of the intermaxillary space. 



Hyopharyngeus, in addition to its usual attachment to the inferior 

 • part of internal surface of superior third of stylohyal, has often 

 another one, quite distinct from the inferior third. "We more fre- 

 quently see the latter in the Horse. 



Hyoideus parvus sometimes absent. 



Hyoffhssns brevis sometimes attached to stylohyoid, generally 

 not. 



Arytanopharyngeus is occasionally well marked. 



Retractor oculi may form a complete investment of the optic 

 nerve, or consist of four bands corresponding with the recti. 



The middle oblique muscle of the eye, as described by Strangeways, 

 occasionally occurs in the Ass. 



The inferior opening of the lachrymal ductus ad nasum varies in 

 position ; generally it opens at the upper part of the anterior naris, 

 thus differing remarkably from the same structure in the Horse. 



Neclc. — Levator humeri never shows the fibrous band indicative 

 of the seat of the clavicle, which this muscle has in the Ox, Pig, and 

 other Ungulates ; but this information is conveyed in some subjects, 

 in which we have seen a small muscle running from levator humeri 

 around the anterior part of pectoralis amicus to the inner side of 

 that muscle, where it disappears. 



Serratus magnus has sometimes a distinct rudimentary division 

 passing to second cervical transverse process, generally only extends 

 as far forwards as the third (see arrangement in Ox). 



Scalenus : instead of terminating by each head at the first rib as 

 in the Horse, the superior division may be prolonged to the third 

 rib or even further back (see arrangement in Ox) over serratus 

 magnus. 



Longus colli we have seen attached only beneath the five an- 

 terior instead of the six anterior dorsal vertebra. 



Back. — Transversalis costarum posteriorly in some cases is laro-e 

 and muscular and blended with longissimus dorsi in the lumbar re- 

 gion ; m others it is tendinous and inserted into first lumbar transverse 

 process. 



Serratus posticus minor varies considerably in its development and 

 attachments. 



iaimmKs rfo;-5« just before its insertion into the humerus varies 

 m its relations with scapulo-ulnaris. Sometimes serial muscular 



