50 



EDENTATA. 



at least in the remains lately described by Mr. 

 Clift, the part joining the sternum, and answer- 

 ing to the cartilages of the ribs, is bony and is 

 connected to the rib itself by a moveable arti- 

 culation. The lumbar vertebra are generally 

 broad and furnished with strong spinous pro- 

 cesses. The transverse processes are incon- 

 siderable in the Slotlis, but large in the. Edentate 

 proper. In the Armadillos the anterior articu- 

 lar processes are particularly strong and larger 

 even than the spiuous. This is the case, but to 

 a less degree, in the Ant-eaters. In the Orycte- 

 ropus there are slight indications of inferior 

 spinous processes on most of the lumbar verte- 

 bra, consisting of a small longitudinal crest. 

 The cuudul vertebra vary excessively in num- 

 ber. In the Unau and Erudypus ilidactylus 

 they are very few not more than seven or 

 eight ; in the large Ant-eater forty, and in the 

 African Manis forty-five. In the remains of 

 the Megatherium lately deposited in the Mu- 

 seum of the Eoyal College of Surgeons, the 

 tail would appear, according to Mr. C lift's 

 computation, to consist of eighteen vertebrae at 

 least. The caudal vertebrae of the Edentata 

 proper have inferior spinous processes of a 

 remarkable form, being constituted of two 

 branches meeting inferiorly in the median line. 

 The Megatherium possesses similar V-shaped 

 processes. In the Myrmecophuga didactyla the 

 two branches are not united in the anterior two 

 of them. The sternum offers a considerable 

 developement of the manubrium or anterior bone 

 in the whole of the Edentata, particularly in the 

 Ant-eaters and Armadillos. It is also rather 

 large in the Megatherium. 



The pelvis in the Edentata proper is much 

 elongated, and the acetabulum rather behind the 

 middle of the whole length of the bones. The 

 ileum, which forms the anterior half of the pel- 

 vis in the Armadillo, is fixed to the sacrum by 

 its posterior portion, a surface of considerable 

 extent. The ischium and pubis are large, the is- 

 chiatic notch wide, and the cavity of the pelvis 

 capacious. In the Sloths and Megatherium 

 the pelvis is of large dimensions, the ilia very 

 broad, especially in the latter; the cavity capa- 

 cious, and the outlet large. The ossa pubis are 

 joined at the symphysis in most of the Eden- 

 tutu, as is now ascertained by Mr. Clift, in the 

 Megatherium. In the Myrmecop/iaga diduc- 

 tyla, it is stated by Cuvier to be open. The size 

 of the pelvis in the Megatherium is enormous. 

 On comparison of it with the pelvis of an 

 elephant eleven feet in length, Mr. Clift found 

 that in the former the ilia are 5ft. lin , and in 

 the latter only 3ft. Sin. 



The anterior extremity. The principal cha- 

 racteristic of the bones of the arm in the Sloth 

 is their extraordinary length. The humerus is 

 very much elongated and cylindrical, with the 

 elevations but slightly marked. The ulna and 

 rniliiis are also very long, and bowed, so that 

 the bones are distant at the middle of their 

 length ; the radius is very broad anteriorly. 

 The very complete power of pronation and su- 

 pination enjoyed by this animal is no less ob- 

 viously suited to its habits than the great 

 length of its anterior extremities; both of which 

 peculiarities are admirably subservient to the 



complicated objects of holding by the boughs, 

 of advancing along their under-surface, and of 

 reaching and bringing to the mouth the leaves 

 on which it feeds ; and the structure of the 

 hand (fig. 35) is no less suited to the same pur- 



Fig. 35. 



Hand of the Sloth. 



poses. The carpus is as long as it is broad ; it is 

 composed of six pieces only, of which four form 

 the first series, and two the second. The os 

 scapho'ides is the largest of the whole, and is 

 articulated with the os semilunarc by a convex 

 articular surface : the os cuneij'orme presents on 

 its ulnar side an oblique flattened surface ; the 

 os pisiforme, which is not named by Cuvier, 

 does however exist, though it is of small size. 

 The inner and larger piece of the anterior series 

 probably consists of the os trapezium, trape- 

 zoideum, and magnum united ; and the external 

 one solely of the os unciforme. In the Unau the 

 os trapezo'ides is distinct. The metacarpul 

 bones, to return to the AV, consist of three per- 

 fect and two rudimentary, the whole of which 

 are united at their base to each other and to the 

 inner solid carpal piece, consisting of the three 

 bones before mentioned; so that in fact the five 

 metacarpal bones, with the os trapezium, tra- 

 pezoideum,and magnum, form one solid osseous 

 piece. The fingers, which are three only, are 

 very long, and consist each of two moveable 

 phalanges only, the first being very small and 

 early anchylosed to the metacarpal bone. In a 

 very young skeleton in my possession, these 

 bones are not yet united. There is but very 

 little flexion between this part and the second 

 phalanx, but between the latter and the third or 

 ungueal phalanx the flexion is complete, the 

 latter being bent down to the palm with perfect 

 ease. These ungueal bones are very long, 

 curved, laterally compressed, large at the base, 

 at which part there is, as in the cats, a bony 

 sheath to cover the base of the claw ; and the 

 latter envelopes the phalanx for about five-sixths 

 of its length. 



The posterior extremity in this remarkable 

 animal offers no less striking peculiarities. 

 The breadth and openness of its pelvis have been 

 already noticed. The/ewuris articulated to the 

 acetabulum so as to stand obliquely outwards 

 from the pelvis ; it has a short head, and is it- 

 self rather short, strong, and flattened. The 

 tibia a\\A fibula are long and slender, and some- 

 what curved ; the superior articular surfaces of 

 the tibia are flat, that of the inferior extremity 



