202 SHOULDER-GIRDLE AND BREAST-BONE. 



meso-sternal segments (m. st. 3, and m. st. 7) : this is the more to be wondered at by the mor- 

 phologist, for the right and left sternal moieties in the mid-region had quite coalesced in the 

 young individual (see fig. 8) ; but we see that the primordial fissure opens again in these places, 

 to be perfected into synovial cavities (see figs. 3 and 6, sy.) The feebly ossified sternal ribs 

 become extremely compressed, and are of great width from below upwards, where they articulate 

 with the sternal pieces fore and aft of them (see fig. 5, s. r., which shows the lower end of the 

 fourth sternal ribs and the front of the double third meso-sternal) : they are more than flush with 

 the sternal segments : these latter articulate with each other by much smaller synovial facets (see 

 figs. 4 and 5, m. st.). The joint between the vertebral and sternal ribs from the fifth arch, 

 backwards, does not acquire a cavity (fig. 7, v. r., s. r., f. r.). 



The "metosteon" only ossifies the front half of the handle of the great xiphoid blade ; and the 

 fontanelle is a persistent fissure, nearly an inch in length (fig. 1, m. t. o., x., x. f.). 



In Manis longicauda (figs. 13 17 ; figs. 13, 14, and 17, two thirds nat. size; fig. 15, three 

 diameters; and fig. 16, nearly one and a half diameters) the lower half of the thorax is much 

 denser, in its ossification ; there is neither a separate " proosteon," nor a transverse cleft in the "prae- 

 sternum" (p. st.). The first meso-sternal segment is symmetrical, and has a cavity between its 

 halves ; there are behind these three azygous segments, whilst the rest of the meso-stermmi is com- 

 posed of two segments in a connate condition. The whole Sternum is much flattened in this type 

 (see the inverted section, fig. 1 6, which shows the synovial cavities, and the gradual thickening towards 

 the xiphisternum), and becomes very broad behind the ribs (m. t. o.) : the xiphisternum bifurcates 

 between the well-ossified first " metosteon," and grows backwards as two flat, narrow 7 , extremely 

 long " horns ;" the left of these is eight inches eight lines long, the right nine inches six lines ; 

 the rest of the Sternum two inches two lines ; the whole length, on the right side, being eleven 

 inches eight lines. These " horns" are feebly ossified endosteally ; the left ends in a free point, 

 but the right horn is continuous at its supero-posterior end with three abdominal ribs similarly 

 ossified. In front of the foremost of the abdominal ribs continuous with the " horn," is the first 

 of this curious series (figs. 13 and 17, a. r. 1) ; it is unossified, and is fourteen lines in length. The 

 second abdominal rib (a. r. 2) is five inches six lines long ; the third (a. r. 3) five inches two lines, 

 and the fourth (a. r. 4) four inches. The feeble endosteal substance is broken up into several 

 patches in these abdominal ribs ; the space between them and the " xiphisternal horn," from 

 which they have never been cleft at their upper ends, is filled with a peculiar muscle, the counter- 

 part of that which is seen to be quite symmetrical in Pholidotus (fig. 1 2, x., x. m.), which shows 

 the under surface of xiphoid and its muscles. The first six pairs of vertebral ribs do not become 

 segmented from the sternals in Manis ; the rest are so segmented, and the connection is by fibrous 

 tissue (fig. 15, f. r.). The vertebral rib (v. r.) is concave, and the head of the sternal rib (s. r.) 

 convex : they are both flat in Pholidotus (fig. 1 1 -) 1 



The Anteaters are few in number, but these are types of three very distinct Families, 

 the Aard-vark representing one, the Little Anteater another, and the Tamanoir (Ant-bear) 

 and the Tamandua a third. In Orycteropus capensis, the representative of the first of these 



1 This last sub-genus does not necessarily differ from Manis in the xiphisternum ; for the reader 

 may find the long free "horns" in the fine skeleton of Pholidotus Africunus, Gray, in the British 

 Museum. 



