18 Proceedings of the Royal Physical Society. 



blended with the scaphoid. If this were the case, we might 

 reasonably expect that the trapezoid would bear some 

 evidence of the fusion, in the same way that the scaphoid 

 does (as shown by Leboucq, 7). No such evidence could 

 be detected. This, in conjunction with the exceedingly 

 small size of the trapezium in some animals, leads to the 

 conclusion that the trapezium is following in the steps of 

 the metacarpal bone, with which it was originally connected. 



Keferences. 



1. Arloing, S,, " L'Organisation du Pied chez le Cheval," ^nn. 



Sci. Nat., 5me Ser., Zoologie, t. 8, 1867, p. 55. 



2. Percivall, Wm., "The Anatomy of the Horse." London, 



1858. 



3. Chauveau, a,, et Arloing, S., "Traite dAnatomie Comparee 



des Animaux Domestiques," 4me edit., Paris, 1890. 



4. Ellenberger, W., und Baum, H., " Handbuch der vergleich- 



enden Anatomie der Hausthiere," lOte Aufl., Berlin, 1903. 



5. M'Fadyean, J., "Comparative Anatomy of the Domesticated 



Animals." Part I., Osteology and Arthrology. Edinburgh. 



6. Martin, P., " Lehrbuch der Anatomie der Haustiere," Bd. IT., 



Stuttgart, 1904. 



7. Leboucq, H., " Recherches sur la Morphologie du Carpe chez 



les Mammiferes," Arch, de Biologie, t. v., 1884. 



Explanation of Figures. 



Fig. 1. Outline drawing of the inner (medial) side of the horse's carpus. 

 Sc. = Scaphoid. Mg. = Magnum. Tzd. = Trapezoid. Tzra. = 

 Trapezium. M.IL and M.III. = Second and Third Metacarpal 

 bones. 

 The trapezium in the carpus from which this drawing was made is 

 slightly larger than the average. 



Fig. 2. Outlines of four trapezoids. 1 is from a carpus in which there was 

 no trapezium, 2, 3, and 4 illustrate the different levels at which 

 the articular surface for the trapezium may occur. s = surface for 

 scaphoid. i( = surface for trapezium. In 4 the surfaces for 

 scaphoid and trapezium are continuous. 

 Both figures were made from photographs of the actual bones. 



