SOLIPEDA. 



721 



Tarsus. 3, 5, Astragalus or coc-kal bones ; 7, os 

 Calcis; 10, os Cuboides; 11, os Xavieulare ; 12, 

 os Cuneiforme. 



Metatarsus. 14, Upper extremity, and 15, lower 

 extremity of the great metatarsal or cannon bone. 

 16, 17, rudimentary external metatarsal bone; 20, 

 Sesamoid bone. 



Hind-foot. 22. Proximal phalanx, or great pas- 

 tern ; 23. Middle phalanx, or lesser pastern, or coro- 

 nary bone; 24, Last phalanx or coffin bone; 25, 

 Sesamoid bone. 



The leg is in the Solipeda almost exclu- 

 sively formed by the tibia, which is of great 

 strength, and very massive towards its upper 

 extremity, where the ridges for muscular at- 

 tachment stand out in bold relief; inferiorly 

 it becomes more slender, and approaches 

 nearer to a cylindrical shape, expanding again 

 inferiorly to form the articulating surface for 

 the ankle joint. 



The fibula {Jig. 500. 1, 2.) is even more ru- 

 dimentary in its development than the ulna in 

 the anterior extremity, being, in fact, nothing 

 more than a long spiculum of bone implanted 

 among the muscles, and laid like a slender 

 splint along the outer and posterior angle of 

 the tibia, with which it is firmly connected 

 by ligamentous attachments in the vicinity of 

 the knee-joint, whence it descends separated 

 by a small interval from the tibia as far as the 

 middle of that bone, to which at this point it 

 becomes closely applied, and then, gradually 

 becoming more and more attenuated, is to- 

 wards the lower third of the leg completely 

 lost. 



The bones of the tarsus in the horse are, 

 1st, the astragalus, or " cockal-bone," as it is 

 vulgarly named (Jig. 500. 3, 5.), the os calcis, 

 or " heel-bone " (7), the cuboid (10), the 

 navicular (] 1), the middle cuneiform and the 

 lesser cuneiform (12). The internal or great 

 cuneiform bone is here wanting, as also are 

 the bones of the great toe, which, when pre- 

 sent, it is destined to support. 



The bones of the metatarsus, like those of 

 the metacarpus, are three in number, viz. one 

 large central or cannon bone, and two lateral 

 rudimentary pieces. The central piece (Jig. 

 500. 14, 15.), which supports the entire weight 

 of the body, is apparently composed of the 

 conjoined metatarsal bones belonging to the 

 second and third smaller toes; in the human 

 skeleton the line of demarcation between 

 the two being indicated by a deep longitu- 

 dinal groove : by its upper extremity this 

 bone articulates with the three lower bones 

 of the tarsus ; while inferiorly it presents a 

 smooth articular surface, whereby it sup/ports 

 the first phalanx of the foot. The external 

 rudiment {fig. 500. 16, 17.) is an imperfect 

 metatarsal bone, occupying the place of that 

 which in the human subject supports the little 

 toe : by its upper extremity it articulates 

 with the cuboid bone of the tarsus, while 

 inferiorly, owing to the deficiency of the cor- 

 responding toe, it forms no articulation. The 

 internal rudiment represents the metatarsal 

 bone of the first of the small toes in the hu- 

 man foot : superiorly it articulates with the 

 lesser cuneiform bone of the tarsus (12), 



VOL. IV. 



whence, as it descends, it gradually dimi- 

 nishes in size, and is lost before it reaches 

 the foot. 



The bones of the hind foot resemble those 

 already described in the anterior extremity, 

 and are distinguished by similar names, the 

 first phalanx of the solitary toe being the 

 great pastern, the second the little pastern or 

 coronary bone, and the third, or that which 

 supports the hoof, the coffin bone : there are 

 likewise the scsamoid bones (^0), behind the 

 articulation, between the cannon bone and the 

 first phalanx, and also between the coronary 

 and coffin bones (25). 



MVOLOGY. The mjology of quadrupeds 

 is, in many points of view, a subject of 

 particular interest, more especially in those 

 races which are far removed from man in 

 their general habits or in the configuration of 

 their skeleton. In the case of the Solipeds, 

 owing to the exceedingly aberrant structure 

 of their extremities, the disposition of their 

 muscular system becomes a very important 

 subject of inquiry, and it is partly from this 

 cause, and partly from the necessity of ob- 

 taining an accurate knowledge of the anatomy 

 of animals so valuable to mankind, that the my- 

 ology of the horse and its congeners has been 

 studied with great care, and delineated with 

 extraordinary zeal and perseverance. It is 

 for these reasons that we shall in the present 

 article describe at some length this portion of 

 their economy,, premising that the details here 

 given will be found more or less applicable to 

 quadrupeds generally, except where obvious 

 peculiarities of structure belong to the class 

 which forms the more immediate subject of 

 our study. 



Panr.iculus carnosus. On removing the 

 skin, the entire body is in most quadrupeds 

 found to be invested with a muscular cover- 

 ing, the thickness and consequent importance 

 of which varies in different parts. In the 

 human subject the traces of this fleshy pan- 

 nicle are very feeble, being confined to certain 

 regions, such as the anterior part of the neck, 

 the palms of the hands, &c. ; but in the horse 

 it forms a much more important investment, 

 giving mobility to the integument, and ma- 

 terially contributing to the support and de- 

 fence of various organs. This fleshy covering 

 is very thick in the anterior region of the 

 neck, whence it extends downwards upon the 

 anterior extremities, and, becoming tendinous, 

 is extensively inserted in conjunction with the 

 tendons of the latissimus dorsi and teres 

 major, into the external surface of the hu- 

 merus. From this point strong muscular fi- 

 bres pass downwards over the muscles of the 

 fore-arm, where they terminate in a broad 

 fascial expansion which embraces the lower 

 part of the fore-leg. Another strong portion 

 of this fleshy tegument spreads over the sides 

 and loins, where it degenerates into a tendino- 

 membranous layer, extending downwards as 

 far as the penis, which it likewise invents with 

 a carneo-membranous sheath. It likewise en- 

 cases the buttocks and thighs in a strong 

 covering of fleshy and tendinous fibres, which 



3 A 



