84 PROFESSOR OWEN ON THE AYE-AYE. 



the Quadrumana ; yet, as the difference depends on the non-claviculate character of 

 the Carnivora, a remnant only of the clavicular strip of the muscle being present in 

 those with small free clavicular bones, as the Felines, and being wanting in those without 

 clavicles, we cannot derive the same evidence of the ordinal relations of Chiromys 

 when we extend the comparison to the myology of those of the Lissencephalous group 

 which have complete collar-bones. In the Squirrels, e. g., a clavicular strip exists, 

 which differs from that of Chiromys only in its minor relative size to the sternal portion. 

 The well-developed digastricus, with its distinct intermediate tendon, is a more decisive 

 mark of the Lemurine affinity of Chiromys, as against the Rodents. In the muscles of the 

 jaw of Chiromys, although the masseter has unusual thickness and strength, it retains 

 the character of that muscle in the Quadrumana, and there is no trace of the peculiarly 

 distinct oblique strip, described as an accessory masseter, in the Rodentia, — especially in 

 those with the large antorbital vacuity. In the muscles of the limbs, especially in the 

 tendinous strip uniting the flexor sublimis and flexor profundus muscles for a partially 

 associated action, the Aye-aye resembles the Tarsius dissected by Burmeister, the 

 Stenops dissected by Vrolik, and the Perodicticus dissected by Van der Hoeven. 



Comparison of the Brain. — The brain of the Aye-aye, by the proportion and relative posi- 

 tion of the cerebrum to the cerebellum, andby the fissures and folds of the cerebral surface, 

 determines Chiromys to be a member of the wave-brained section of Mammalia, Gyrence- 

 phala ; and in that section it most resembles, in the number and disposition of the primai-y 

 convolutions of the cerebrum, as well as in general shape and proportions, the brain of 

 Lemur proper. The brain of the little Tarsier ( C. tarsius), whilst exhibiting the more con- 

 stant and essential gyrencephalous character, as do other diminutive species, in the exten- 

 sion of the cerebrum over the cerebellum, shows an almost entire absence of superficial 

 fissures. In that of the Tarsius figured by Burmeister ', the fore part of the sylvian fissure 

 and the short vertical fissure in the sylvian fold are all the traces of convolutions which 

 are indicated. In the brain of the Javanese Slow Lemur (Stenops javanicus), described 

 and figured by Schroeder Van der Kolk and Vrolik, the sylvian fissure extends to 

 the upper surface of the cerebrum ; the Aye-aye, in this respect, being intermediate 

 between Stenops and Tarsius. The sylvian fold, in Stenops, is also indented by the 

 vertical fissure, which is more wavy than in Chiromys or Tarsius ; but the suprasylvian 

 and medio-longitudinal fissures are wanting in Stenops as in Tarsius. Stenops, however, 

 shows the bifurcate anterior ends of the medio-longitudinal fissure, and a transverse 



intacte. II est dvident qu'on en a retire, apres I'empaillage, le tarse aujourd'hui manquant, et tout fait supposer 

 (je ne puis dire atteste, parceque la piece n'est pas sous mes yeux, et qu'il ae subsiste aucuae note au sujet de 

 cette operation) que le tarse figure' comme etant celui de 1' Aye-aye est bien, comme tous I'avez suppoad, le tarse 

 du Galago crassicaudatus. 



" J'ai pens^ que ces details vous feraient plaisir, et je tous les communiquer imm^diatement. 



" Croyez a naon entiere consideration et a mon aifectueux deVouement, votre tres-empresse', 

 " P''™' 28 Octobre, 1862." ..p^„i^ Gerva.s."] 



' Op. cit. p. 30, pi. l.figs. 1-4. 



