TUE BRAIN OF THE HEDGEHOG. 379 



.les, one of which arises from the prominent end of the tibia, 

 and the other from that of the fibula. The tendons of both 

 pass behind the inner malleolus, and that of the former mus- 

 cle goes to the tibial and plantar surface of the hallucal meta- 

 tarsal, vrhile the latter is inserted into the ento-cuneiforni 

 bone. The interossei 2>eclls are represented by a pair oijlex- 

 ores breves for each digit except the hallux. 



The adult Hedgehog has thirty-six teeth, of which twentj' 

 are in the upper, and sixteen in the lower jaw. The dental 



* 1 . .3-3 0—0 4 — 4 3 • 3 nn 



formula is ^. 3-7^ c. ^z:^p.'n%. -^^ m. ^ = 6b. 



The grinding surface of the crowns of the first and second 

 upper molars exhibits a jDattern fundamentally similar to that 

 of the corresponding teeth in Man, the Anthropoonorpha^ and 

 the majority of the Lemurs ; that is to say, there are four 

 cusps, and the antero-internal is connected with the postero- 

 external cusp by an oblique ridge. The cusps are remarkably 

 sharp and pointed, and the outer surface of the postero-ex- 

 ternal one alone is somewhat inflected. 



In the lower jaw, the corresponding molars are each marked, 

 as in most Lemurs, by two transverse ridges. In front of the 

 anterior ridge is a basal prolongation of the tooth, on to which 

 a curved ridge is continued inward and forward from the an- 

 terior principal ridge, giving rise to an imperfect crescent with 

 its convexity outward. 



According to Rousseau there are twenty-four milk-teeth, 



e. 4—4 d.m. p^) which fall out seven weeks after birth. 



The brain of the Hedgehog is remarkable for its low or- 

 ganization. The olfactory lobes are singularly large, and are 

 wholly uncovered by the cerebral hemispheres ; which, on the 

 other hand, do not extend back sufficiently far to hide anj 

 part of the cerebellum. Indeed, they hardly cover the corpora 

 quadrigemina. Only a single shallow longitudinal sulcus 

 marks the upper and outer surface of each hemisphere. On 

 the under surface, a rounded elevation corresponds with the 

 base of each corpus striatum. Behind this, another elevation 

 represents the end of the uncinate gyrus and the termination 

 of the hippocampus major ; and therefore answers, in a man- 

 ner, to the temporal lobe. The inner face of the hemisphere 

 presents neither convolution nor sulcus, except -behind and 

 below, w^here a very broa^^^M|g|jpn follows the contour of 

 the fissure of Bichat and i^^HBix^and represents the dentate 

 sulcus. Above, this sulci^ends behind the posterior margin 



