73 



The arytenoid cartilages present the šame peculiarlty as in the above- 

 nanied animal, being continuous with each other at iheirapices. Thia 

 adhesion does not of course prevent their being drawn apart at their 

 bases vvhere the chordce vocnles are attached ; the crico- and thyreo- 

 arytenoidei being strongly developed for that purpose. The chordce 

 vocales are distinct shining ligamentous threads ; the crico- thyroidei, 

 vvhich render these chords tense, were largely developed, covering the 

 vvhole of the anterior space between the two cartilages to which 

 they are attached. They are no doubt materially concerned in pro- 

 ducing the sharp cry of this animal. The sacculi laryngis are narrow 

 but deep. The epiglottis is broad and of a rounded form ; it has a 

 linear depression at its base, and a longitudinal ridge along the middle 

 of its posterior or laiyngeal surface, which fits into the rinia glottidis 

 vvhen the cartilage is depressed. The margin of the soft palate was 

 in close contact vvith the tongue anterior to the epiglottis, which, to- 

 gether vvith the apices of the arytenoid cartilages, rose into the pos- 

 terior nares ; the structure, indeed, seemed to forbid the epiglottis 

 passing under the soft palate, although we mušt suppose it to do so 

 when the shrill cry is produced ; but the grunting noise appears to be 

 emitted by the nose. 



" The tongue corresponds in form to the space between the two 

 rovvs of inferior molares ; is compressed lateraliy, and deeper than it is 

 broad. It grows gradually narrower to the apex, vvhich is neatly rounded 

 and is impressed vvith small follicular apertures. Half an inch of the 

 extremity only is free. The papillce on the surface are estremely mi- 

 nute ; tovvards the dorsum they are conical and retroverted, and nu- 

 merous delicale lines converge tovvards the root of the tongue. Likę 

 the Acouchy, it vi'ants the elevated or super-imposed portion observ- 

 able in the Beaver and Guinea-pig. 



" The parietės of the pharynz are extreniely thick ; the istkmus 

 fauciumis long, narrovv, and conical, diminishing backvvards, as in the 

 Beaver; the sides are not produced into folds, but the vvhole of this 

 structure is evidently adapted to the šame end, as was first pointed out 

 by Mr. Morgan in the structure of the faitces oi the Capybara. The 

 inner membrane of the cesophagus is disposed in longitudinal rugcB. 



" The eye is stated by M. Desmarest to be moderately large, but the 

 largest diameter of the globė does not exceed 5 lines j the apparent 

 magnitude is ovving to the great proportion in the cornea, the diameter 

 of its base being only one line less than that of the globė itself. This 

 large size of the cornea is found in most of the Rodentia, especially 

 in those whose habits are nocturnal. It prevails also in the Lemu- 

 rid<p ; and is evidently for the purpose of admitting as much light as 

 possible into the globė. The loss of refractive povver is in most of these 

 cases compensated by a greater convexity in the lens; vvhich in Ca- 

 promys is 3 lines in the long and 2 in the short diameter. The 

 ronjunctive membrane has a brovvn stain round the margins of the 

 cornea; the ręst is white and of a firm texture. The sclerotic is so 

 thin as to be discoloured by the pigmentum nigrum beneath, so that 

 the anterior half is nearly black ; vvhich, vvhen seen through the vvhite 



