218 



QUADRUMANA. 



brachiura is less firm, by which the hand 

 acquires a great deal of mobility, and can be 

 inclined, as I have often observed, not only 

 outwards, but also backwards. With regard 

 to the posterior extremities, the principal 

 deviation is offered by the Tarsius, in which 

 the fibula is but a slender filiform bone, not 

 extended to the tarsus, but terminating on 

 the third inferior part of the tibia, with which 

 it is united. Consequently the tarsal articu- 

 lation is only united with the tibia. A 

 yet more striking peculiarity is exhibited in 

 Tarsius and Ololicnus by the tarsus, in which 

 the calcaneum and the scaphoid bone are 

 two long styliform bones, contributing in 

 that way to produce the enormous length 

 of the posterior extremities. In the Stenops 

 there is not so great a deviation from the 

 ordinary form to be observed ; but it is, how- 

 ever, of some interest, that the two Malleoli 

 are very small, and that the astragalus has an 

 oblique direction inwards. The results of this 

 disposition, as I have proved more minutely 

 in the said paper, are a greater mobility of the 

 foot, a direction upwards of its internal edge, 

 and a great interval between the thumb and 

 the other digits. 



MYOLOGY. I can only mention the mus- 

 cles of the Stenops, having had no opportunity 

 to dissect the other genera of Leumrince. 

 The sterno-mastoideus has a distinct clavicular 

 fascicle, the existence of which is very interest- 

 ing, while it is not found in some monkeys, 

 nor in any of the mammalia which have no cla- 

 vicles. In the A/, digastricus there is but an in- 

 dication of intermediate tendon ; consequently 

 the muscle is simplified, and passes into the 

 form it has in the Carnivora, in which it is 

 composed of a single fascicle. Another pecu- 

 liarity in the muscular system of the Stenops 

 is the existence of the omo-hyoideus, which is 

 wanting in many large Mammalia, but exists 

 in the monkeys, and as my dissection has 

 proved in the Dasyurus, the Ursus arctos, the 

 Ptcropus, and the Opossum. This muscle is 

 also one of the links connecting the genus 

 Slcnops with the Quadrumana on one, and 

 with the Carnivora on the other side. The 

 lathsimus dorsi gives, in the same manner 

 as in so many other climbing animals, a pro- 

 longation to the internal condyle of the hu- 

 merus. The pectoraMs magnus has the length 

 and the strong disposition of fibres, proper to 

 all the quadrupeds. As in them, the clavi- 

 cular fascicle is not much developed. The 

 disposition of the bleeps and brachialis interims 

 is interesting, because it proves that the genus 

 Stenops, and probably the other LemurincB, 

 form a transition from the Quadrumana to the 

 Carnivora insectivora. In the same manner as 

 in these, the biceps consists of but one fascicle, 

 which arises from the superior edge of the 

 articular cavity of the scapula, and is inserted 

 into the radius, and the brackialis interims pos- 

 sesses but an external fascicle, which passes 

 to the antibrachium, behind and under the 

 biceps. It is very remarkable, that notwith- 

 standing the want of the internal fascicle 

 of the biceps, there is a coraco-brachiatis. 



It is prolonged downwards to the internal 

 condyle of the humerus ; between it and the 

 internal fascicle of the triceps passes the cu- 

 bital portion of the vascular plexus. This is 

 an exception to the rule, that the existence of 

 a coraco-brachialh is connected with the ex- 

 istence of an internal fascicle of the biceps, 

 and an additional proof that the genus Stenops 

 forms a transition from the Quadrumana to the 

 Carnivora. In the antibrachium the prona- 

 tores and supinatores are very strong. The 

 JJexores are the radialis and ulnaris interims, 

 with the palmaris longus. The extensores are 

 the radialis externus longus et brevis, with the 

 ulnaris externus and the extensores of the 

 fingers. For the flexion of the fingers, there 

 is a riidi mental flexor superficialis, which is 

 wanting in the Carnivora, and which exists, 

 on the contrary, in the Quadrumana. 



Instead of the abductor magnus and extensor 

 brevis pollicis there is but one muscle, formed 

 by the union of both these muscles. I have 

 shown already that this tendency to simplify 

 is yet observed in the Orang-wtan and in the 

 Mandrill, and more distinctly in the I mil. 

 Besides this the thumb of the Stenops pos- 

 sesses a flexor brevis, an abductor brevis, and an 

 adductor pollicis. 



In the posterior extremities we observe, 

 first, a very long and very strong psoas, 

 composed of two portions, of which the in- 

 ternal is the strongest. They are united to the 

 iliacjis interims and attached to the small 

 trochanter. Thesartorius has an oblique di- 

 rection, and is attached to the internal edge 

 of the tibia. The gracilis is broad and attached 

 lower to the tibia. The rectus femoris, the 

 cruralis, vastus externus and interims have their 

 usual disposition. There is no pectinceus, 

 but there are three adductores. It is very re- 

 markable that the adductor magnus forms no 

 aponeurotic canal for the passage of the plexi- 

 form crural artery, but that this passes only 

 on the superior margin of the adductor magnus, 

 and penetrates in this manner into the popli- 

 teal cavity. I have stated the same disposi- 

 tion in the Bradypus didactylus, in which, and 

 also in the Stenops, this deviation seems to be 

 connected with the peculiar ramification pro- 

 per to the vessels of the extremities, by which 

 they are more preserved from compression, than 

 in the animals, in which the crural artery forms 

 but a single tube. On the posterior surface 

 of the thigh there are a semi-tcndinosus, semi- 

 membranosus and biceps. The semi-tendinosus 

 is united to the gracilis. The semi-mcmbrano- 

 sus has its own insertion. They descend very 

 low and surround the gastrocnemius. The 

 biceps terminates on the superior part of the 

 tibia with a large muscular fascicle. Theg/u- 

 tceus maximus has a large insertion on the 

 thigh, and is inserted very much downwards. 

 On the anterior crural surface there are a 

 tibialis anticus, an extensor magnns and brevis 

 digitorum pedis, and extensor brevis hallucis, 

 which has a very oblique direction, and aper- 

 oiiceus mngnus and brevis. As regards the 

 flcxores, I have only to mention the union of 

 thcjlt-xor magnus hallucis with the./'t.iw mag- 



