QUADRUMANA. 



219 



nus quatuor digitorum pedis, which are united 

 in the same manner as in the monkeys. They 

 both give tendons to the toes, of which each 

 receives consequently two tendons. The plantar 

 surface of the tendon of the flexor magnus qua- 

 tuor digitorum give off four lumbrical muscles. 

 Instead of a. flexor brevis there are but small 

 tendons, which bifurcate for the passage of 

 the tendons of the flexor magnus ha/lucis, and 

 flexor magnus' quatuor digitorum pedis. The 

 tibialis posticus is very strong. The small mus- 

 cles of the posterior thumb or great toe are 

 the abductor, the flexor brevis, and the adduc- 

 tor. Their strength is connected with the 

 mobility and with the removed position of the 

 posterior thumb, giving a great deal of agility 

 to the Stenops in his climbing motions. 



NEUROLOGY. Theencephalon of the Lemu- 

 rincB is only known by the dissection of the 

 Lemur mongos and of the Stenops javanicus 

 and tardigradus. Science is indebted for the 

 first to TIEDEMANN, and for the two last to 

 SCHRODER VAN DER KOLK and to myself. The 

 encephalon of Lemur mongos seems superior 

 to that of Stenops, by the larger development 

 of the hemispheres, the greater breadth of the 

 anterior lobes, the more numerous convolu- 

 tions and deeper anfractuosities, but otherwise 

 they offer the same type. I have minutely 

 described the brain of the Stenops tardigradus 

 in my paper on this animal, and I mentioned 

 there the small development and the asyme- 

 try of the hemispheres (fig. 139), the triangu- 

 lar form of the anterior lobes, the few convo- 



Fig. 139. 



Brain of Stenops tardigradus. (After W. Vrolik.~) 



lutions,the shallow anfractuosities, the scarcely 

 indicated fossa Sylvii, the not prominent pons 

 Farolii, the very thick cerebral peduncles 

 (crura cerebri), the want of corpora candicantia, 

 the short corpus callosum. In all these points 

 the brain of the Slenops is inferior to that of 

 the monkeys, from which Stenops differs also 

 by more imperfect intellectual faculties. 



For the organs of sense, I mention princi- 

 pally the interesting existence in the Stenops, 

 of the tapetum lucidum in the eye, by which 

 the animal acquires the faculty of reflection 

 of the light, improperly called phosphorescence 

 of the eyes. In general the sensibility of the 

 eye to light is very exquisite. Therefore most 

 LemurincB are nocturnal, and see very well in 

 almost profound obscurity, as is proved by 

 the observations of F. Cuvier, in the Lemur 

 mur'mus. The ears of Stenops are very large ; 

 the concha deep, the tragus and antitragus ele- 

 vated, and instead of anthelix there are two 

 prominent and almost parallel cartilaginous 

 plates. The same development of the ear is 

 observed in the genus Otolicnus. This great 

 development in a nyctalope animal is an inter- 

 esting fact, principally by comparison with 

 the Cheiroptera, in which the same disposition 

 occurs. The tongue of the Stenops offers a 

 strange structure in the existence of a cartila- 

 ginous plate, by which it is supported, and the 

 anterior margin of which is denticulated. 



ANGEIOLOGV. I only know some peculiari- 

 ties about the heart and the vessels of the 

 Stenops. It has a rounded and plane form ; 



the right ventricule is scarcely longer than the 

 left, and terminates in a rounded point. The 

 right auricle is much larger than the left. The 

 distribution of the trunks coming from the 

 arcus aortce is as in the plurality of Mamma- 

 lia, viz. three trunks coming from the a. inno- 

 minata, and a separate left subclavian artery. 

 But the most interesting is the ulterior distri- 

 bution of the arterial and venous vessels in the 

 extremities. Sir A. CARLISLE was the first 

 to show, that they form plexuous ramifications, 

 consisting of a large number of narrow cylin- 

 drical vessels anastomosing together. Eighteen 

 years ago, I repeated the observations of this 

 excellent anatomist on various animals, and 

 confirmed their veracity against the objections 

 of OKEN and GAIMARD ; and recently I had 

 again the opportunity to show, that these ra- 

 mifications exist in three species of Stenops ; 

 that in the same manner as has been proved for 

 the Bradypi, by SCHROSDER VAN DER KOLK 

 and OTTO, they consist not only of arteries, 

 but also of veins ; and that, by dividing in 

 branches, these ramifications become smaller 

 and smaller, and composed of a less number 

 of vessels (flg. 140). 



SPLANCHNOLOGY. The stomach has in Ste- 

 nops a rounded, almost globular form, in which 

 the cardia is near to the pylorus, and the ccecal 

 sac much developed. Consequently the con- 

 cave margin of the stomach is small, the con- 

 vex, on the contrary, large ; with these is 

 connected the elongated spleen. This dispo- 

 sition of the stomach, and especially the 



