116 ANATOMY OF VERTEBRATES. 



homologues could be traced from species to species in that family, I 

 distinguished most of them by names. 1 further entered upon their 

 classification, and denned the ' primary ' and ( secondary ' fissures 

 and folds, showing that the e secondary fissures were in general 

 less symmetrical than the primary ones ' (XLVII". p. 134), and 

 that the differences observable in the brains of the Felidcs were 

 due chiefly to the absence of more or less of the secondary convo- 

 lutions in the smaller species; ( in the common Cat the principal 

 fissures, or anfractuosities, are less obscured by fissures of the 

 second degree than in the larger Felines' (ib. p. 133). ] INI. 

 Leuret, in citing this attempt to bring the convolutions within 

 the domain of comparative anatomy, 2 has extended, in association 

 with his colleague, M. Gratiolet, the like comparison to other 

 species and families of Mammalia. Foville 3 arranges the cerebral 

 convolutions into those of the ' first,' ( second,' ( third,' and f fourth 

 orders,' characterised partly by position, partly by direction ; and, 

 in each order, they are subdivided into ' groups.' This system, 

 based mainly on the study of the parts in the human brain, has 

 its utility limited to Anthropotomy ; the comparisons not having 

 been carried to the extent requisite for defining the cerebral fis- 

 sures according to their order of appearance or constancy in the 

 Mammalian series. Prior to the appearance of both these works 

 T had continued my observations as opportunities presented them- 

 selves ; and gave the result of such extended comparisons in the 

 Course of Lectures delivered at the Royal College of Surgeons 

 of England in 1842 : my diagrams there, in which homologous 

 convolutions are indicated by colours, may still testify in part to 

 the extent to which the comparisons had been carried ; the main 

 aim which I had in view beino; the determination of the homolo- 



o 



gous and superadded convolutions in the more complex prosen- 

 cephalon of Man. 4 



In the Carnivora, to the rhinal, figs. 90, 92, 2, hippocampal, fig. 

 so 86, 4, callosal, ib. 7, and sylvian, fig. 90, r 5, 



fissures, are added, in the smallest species 

 (Putorius), the fissures 8 and 14, fig. 87. 

 The first, commencing near the posterior part 

 of the hemisphere, at 11, extends forward, 

 equally bisecting that part of the surface 



inner surface of hemisphere, between the interhciiiispheral and sylvian 



(5) fissures, then bends outward parallel 

 with and in front of the sylvian fissure. That marked u extends 



1 The preliminary sketch of the h'story of this part of cerebral anatomy is from the 

 13th Lecture of the Huutcrian course fur 1842. 2 xi.r - . vol. i. p. 380. 



3 xxv. (181-1). 4 'Medical Times,' Nov. 12, 1842, vol. vii. p. 101. 



