116 ON THE MORPHOLOGICAL CONSTITUTION OF 



rior margins of the intermaxillary bones which form the hsemal 

 arch of the succeeding sclerotome, there are generally a number 

 of variously modified cartilaginous pieces. These pieces are 

 teleologically highly important elements of the rhinal sclero- 

 tome. Morphologically they are actinapophyses. A\Tien fully 

 developed, they are three on each side attached to the alar 

 cartilage. In the ox and other ruminants, the superior actina- 

 pophysis is an irregular lamina, which, imbedded in the fibrous 

 membrane, assists in supporting the wall of the nostril. The 

 second is a thick, short bar, articulated to the alar cartilage in 

 front, and jointed behind to the corresponding element of the 

 vomerine sclerotome, by which arrangement it is immediately 

 connected with the inferior turbiual bone, which is an actina- 

 pophyseal element of the ethmoidal sclerotome. The third or 

 inferior rhinal actinapophysis is a crutch-like cartilage, articu- 

 lated to the alar element by its stem, which is bent inwards, 

 then downwards, and outwards to the margin of the nostril, 

 which it supports by its curved transverse portion. In the 

 bear, racoon, and coati, the two superior actinapophyses are 

 much developed, and, along with the neurapophyseal, form 

 the cartilaginous wall of the trunk-like nose, or pseudo- 

 proboscis. In the phacochoer the acuminated nasal bones 

 curve down toward the intermaxillary, so as to separate the 

 neural elements of the rhinal sclerotome from one another. 

 The rhinal centrum is therefore much diminished in extent ; 

 hut is, at the same time, strengthened for the support of the 

 nasal buckler by a deposit of bone. The htemapophyseal and 

 actinapophyseal elements are thus pushed outwards, along 

 with the nostril, so as to produce that breadth for which the 

 snout of this pig is remarkable. In man the rhinal actinapo- 

 physes are reduced to the sesamoid cartilages. In the solipeds 

 they disappear altogether. The so-called semilimar cartilage 

 of the horse is, in fact, the alar cartilage itself, the internal 

 inferior angle of which, much elongated, supports the inner 



