QUADRUMANA. 



217 



nectecl with those upon the Ccbince, in which 

 I said that the form of the bony framework 

 passes gradually and in a descending line into 

 the form oftheLemurirus, and by those into the 

 form of the smaller Carnivora and Insectivora. 

 The truth of this assertion will be proved by 

 the examination of the skull. In all the skulls 

 of the above-mentioned genera of LcmurincE, 

 the orbits are open posteriorly, and most so 

 in the Galeopithecus (jig. 137), which we shall 

 take as type, and in which there is a large 

 distance between the orbital process of the 

 frontal and of the zygomatic bone united to- 

 gether in Tarsius, lAchanotus, Stenojjs, Otoiic- 

 nus, and Lemur, and forming there a boun- 

 dary for the open orbit. In all the Lemurin<s 

 there is a double frontal bone, with two nasal 

 bones, which are universally very long, and 

 protracted to the anterior part of the muzzle, 

 principally in Stenops, in which they form a 

 sort of tube with the intermaxillar bone. The 

 facial suture of the intermaxillar bone is in 

 general distinct. The lacrymal canal is situ- 

 ated not in the orbit, but on the facial surface 

 of the superior maxillary bone ; in Cheirogaleus 

 (Jig. 138) and Lemur, there is a regular oval 



Fig. 138. 



Skull af the Clieirogaleus Commersonii. ( Original, 

 Mas. Ley den.) 



opening, in the zygomatic bone, similar to 

 that, which I described in Lagothrix, Mycetes, 

 and Ateles. In the glenoid cavity of the tem- 

 poral bone there is a vertical ridge to prevent 

 the backward dislocation of the lower jaw. 

 The coronoid process of the lower jaw is very 

 distinct, as in all the animals, in which the 

 orbits are open posteriorly, and the chin is 

 more depressed than in the Monkeys and 

 Cebincs. 



In the vertebral column the cervical vertcbrte 

 are seven in number. The anterior vertical 

 ridges of the transverse processes, in the pos- 

 terior cervical vertebrae, are more developed 

 than in the Cebince, and extended over a larger 

 number of vertebrae. The spinal process of the 

 epistrophaeus has the quadrangular form with 

 the posterior cutting edge of the Carnivora. 

 In the dorsal vertebrae, the tendency to the 

 form of the lower orders of Mammalia is still 

 more distinct, firstly in their augmented num- 

 ber, which is in general 13, but increases to 15 

 or 16 in Stenops. The spinal processes offer 

 the opposite direction which is proper to the 

 inferior orders of Mammalia, excepting in Stc- 

 nops and Lichanotus, in which they are all 

 inclined backwards. The bodies of the dorsal 

 vertebras are in general all of the same size, 

 and they do not augment, as in the higher 

 order of monkevs of the Old World. In the 



lumbar vertebras there is also an augmentation 

 of number, which varies from 6 8 or 9. In 

 Lemur the form and direction of the spinal 

 lumbar processes have much analogy with 

 those of the Carnivora, being incurvated and 

 directed forwards. In Stenops, Otolicnus, and 

 Lichanotus, they have a more quadrangular 

 form. The styloid processes are much deve- 

 loped. The transverse processes are strong, 

 quadrangular, and directed forwards, as in 

 the Carnivora. The sacrum has the form of 

 a large quadrangular bone, with sharp and 

 straight edges, united by one, two, or three 

 spurious vertebrae with the iliac bones. The 

 form of the pelvis resembles that of the Car- 

 nivora. The iliac bones have two surfaces, 

 an anterior or internal, slightly convex and 

 narrow, a posterior or external, concave and 

 broad. They unite together in a sharp, an- 

 terior edge, of which the anterior and interior 

 iliac tuberosity forms the anterior and inferior 

 termination. The horizontal branches of the 

 pubis are very distant, and make the pelvis 

 pretty large. By this disposition and by the 

 inclination of the pelvis, it resembles very 

 much that of the Carnivora, and especially of 

 the Cercoleptes caudivolvutus, which has so 

 many other points of analogy with the Lemu- 

 rinec. The thorax is compressed, but the ribs 

 are not very convex, as in most of the Car- 

 nivora. In the Sternum there is scarcely a 

 manubrium, but its body is separated into as 

 many long and narrow segments or Sternebra: 

 as there are true ribs. In the scapula, the 

 coracoid process is recurved and directed 

 downwards, as in the Squirrels and other 

 claviculated Mammalia. This is, as I have 

 said before, a distinct manifestation of infe- 

 riority. In the humerus there is, in general, 

 an aperture in the internal condyle for the 

 passage of the brachial artery and the median 

 nerve. 



The fore-arm has a different disposition in 

 the various genera. In most of them it is 

 composed of the two ordinary bones, the 

 radius and the cubilus, of which the radius 

 is in general curved outwards, and the cu- 

 bitus straight. But in the Galeopithecus, the 

 transition to the form of the Bats appears 

 in the disposition of the ulna, which is 

 imperfect, not prolonged to the carpus, but 

 terminated in a slender filiform extremity, 

 which is united with the radius. In the 

 hand, the quadrumanous type is visible in 

 the thumb, which is separated from the 

 other fingers, even in the Galeopithecus. But 

 in no genus of the Lemurimx is the form of 

 the hand so peculiar as in Stenops. Its prin- 

 cipal character consists in the shortness of 

 the index, and in the proportional length of 

 the thumb and of the fourth finger, which is 

 the longest. The carpus is composed of the 

 same number of ossicles as in the monkeys 

 of the Old World ; but as I have proved in 

 another paper*, its connexion with the anti- 



* W. Vrolik, Rech. d'Anat. Comp. sur le Genre 

 Stenops d'llliger, in N. Verhand. d. eerste classe 

 van het Kouiukl. Nederl. Instituut. Amsterdam, 

 D. ix. 1843. 



