214 SHOULDER-GIRDLE AND BREAST-BONE. 



Ordo" CHEIROPTERA." 



Examples. Scotophihis, Plecotus, Molossus, Pteropus. 



The Cheiroptera do not appear to be far removed from the Insectivora ; and although their 

 limbs, especially their fore-limbs, are modified considerably in relation to their habits, yet, the 

 morphology of the two groups is essentially the same. The scapula has its infra-spinous part 1 

 greatly developed, and in some instances outdrawn as in Birds, leaving the supra-scapula a mere 

 angle (Plate XXVIII, fig. 18, sc., s. sc.) ; the pra-scapula (Plate XXVIII, figs. 1113, p. sc. 

 Scotopkilus, 5 diameters, and fig. 18, p. sc., Molossus, 2J diameters) is narrow, and projects 

 forward; the meso-scapula (figs. 12, 13, and 18, m. sc.) is short and moderately high; but its 

 acromion process (ac.) is large and simple, and stands out from the neck of the scapula. The 

 infra-spinous region (sc.) is divided, by a ridge, into two fossae in Molossus (fig. 18), and by two 

 ridges into three fossse in Scotopkilus (fig. 12) ; the sub-scapular plane is sub-divided into three fossae 

 in the latter (fig. 11); in Molossus there are two very deep valleys. In Plecotus, Molossus (fig. 

 18, cr.) 5 and Pteropus, the coracoid is simple, long, incurved greatly, and ossified separately by 

 ectostosis ; in Pteropus there is an epiphysis at its free end ; in Scotophilus pipistrettus, however, 

 the coracoid is bifurcate, and the upper fork turns towards the pras-scapular hook (fig. 13, cr. 

 p. sc.) ; the glenoid cavity (gl.) is very deep. The clavicles (cl.) are very long ; and in Pteropus 

 they are very stout as well (fig. 9, cl.). The meso-scapular segment is soon lost on the upper end 

 of the clavicle, but the pras-coracoid can be found on the lower end ; it ossifies separately (figs. 9, 

 10, 16, 17, p. cr.). The " oruosternum" is reduced to the form of a cuneiform meniscus; but 

 in the young Pipistrelle, two or three months old, it is seen to be well ossified separately (see figs. 

 14 and 15, o. st., 10 diameters). This is a most instructive condition, connecting the inter- 

 articular fibro-cartilage of those Mammals that have strong clavicles and degenerate omosternals, 

 with those possessing feeble clavicles and long, separately ossified omosternals. 



In the four kinds studied by me, I find an epicoracoid (figs. 9, 10, 11, 14, 15, 17, e. cr.) ; 

 it is a flat, reniform flap of cartilage, feebly ossified by endostosis, and wedged in between the 

 clavicle and first rib (s. r.) .* 



The Sternum of the Bat is very human in appearance, and, indeed, in the degree of its 

 segmentation; for in Scotophilus (fig. 11, p. st., m. st., x.), and in Molossus, there are only two 

 transverse clefts the primary clefts which cut up the whole bar into " prae-," " rneso-," and 

 " xiphi-sternum ;" the two latter segments are not divided in Plecotus auritus ; but in Pteropus, 

 which comes nearer to the Lemurs, there are secondary subdivisions (fig. 9, m. st. 2). The 

 ossification of the Bat's Sternum, however, is the same as in the Insectivora, viz. by ectostosis ; of 

 this I am satisfied by Pipistrelles fresh from the nest, where, so soon, there is an epiphysis (ep.) fore 

 and aft of the first cleft (figs. 11, 15); there are two pairs at this part in Pteropus edulis (fig. 9, ep.). 



1 This is very note-worthy, for these Rear-mice are thoroughly Mammalian in every particular ; 

 and their power of flight is not obtained at the expense of any Class-character : although akin to the 

 Insectivora, they are above them; and pass towards the Lemurs, through the Flying-cat and the 

 Aye-aye. 



