PROFESSOR OWEN ON THE AYE-AYE. 51 
twisted on itself. The surface on its anterior or inner border which it gives to the 
clavicle (ib. fig. 12, ss) is 3lines long. The length of the acromion (fig. 13, a) is 6 lines ; 
that of the coracoid (7b. s2) is 7 lines : it is asimple compressed process, 2 lines in breadth. 
The subscapular surface (Pl. XXI. fig. 13) has a shallow channel parallel with the origin 
of the spine, below which it is convex transversely ; it is gently concave lengthwise 
at the fore part; there are no intermuscular ridges or crests on this surface. The 
glenoid cavity (ib. fig. 12, 0) is a long oval, 6 lines by 3 lines, with the apex above, 
and rather produced. The clavicle (ib. ss), 1 inch 5 lines in length, has a double bend 
upward and outward, and a half twist on itself: the sternal end expands to a breadth 
of 3 lines ; the acromial end is more gradually and less expanded. 
The head of the humerus (PI. XXI. fig. 15) has a long-oval form, regularly convex, 
and surpassing in both breadth and length those dimensions of the glenoid cavity. 
The great tuberosity projects on one side to the same height ; the small tuberosity is 
somewhat lower. A sharp deltoid ridge (ib. fig. 14, d) extends from the fore part of the 
great tuberosity halfway down the shaft. The anterior flattened surface meets the 
posterior convex surface of the upper half of the shaft at an obtuse ridge along the 
inner side. The supinator crest (ib. s) begins below the middle of the shaft, near its 
back part, standing well out, and thence passes in an almost straight line to the ecto- 
condyloid tuberosity (c): it equals two-fifths the length of the humerus. The internal 
ridge projects from nearly the fore part of the distal fourth of the shaft, bridging over 
the humeral artery and median nerve on its way to the entocondyloid tuberosity (e), 
where it coalesces with a shorter and sharper ridge, completing the epicondyloid fora- 
men. The inner tuberosity is much more prominent than the outer one. The fore 
part of the lower third of the shaft is convex transversely ; the back part (fig. 15) is 
concave. The anconeal fossa is oblong, of moderate depth, and imperforate. The 
tubercle (r) for the radius forms nearly half of the fore part of the elbow-joint ; the 
back part is exclusively formed by the well-defined trochlear cavity (w) for the ulna. 
The humerus (PI. XIX. ss) reaches to the tenth rib, when bent upon the chest. 
The radius (ib. s) is of equal length with the humerus, and offers no peculiarities for 
description ; the head is nearly circular. The articular cavity at the head of the ulna (7b. ss) 
forms a laterally emarginate semicircle ; below its outer side is a flat surface for the radius ; 
the ulnar side of the bone below the cavity shows a longitudinal fossa: the upper half of 
the bone is bent, with the convexity backward. The ulna is the longest bone of the 
fore limb ; it is compressed below the humeral joint, and gradually narrows to the lower 
fifth of the shaft, which is three-sided, with two of the dividing angles sharp ridges. 
The wrist-bones (Pl. XIX. ss, Pl. XXI. figs. 17, 18) are ten in number, including a 
supplemental sesamoid on the outer side of the scapho-trapezial joint. The scaphoid 
(ib. fig. 18, s) is the longest, presenting its convex articular surface to the outer two- 
thirds of the radial concavity (7b. fig. 17, s:), and articulating with the lunare (ib. fig. 18, 1), 
. which completes the wrist-ball ; at its distal surface it joins the ‘ intermedium’ (7), 
H 2 
