ZOOLOGY 



SECT. 



across the cavity from the tympanic membrane, and is fixed 

 internally into the membrane covering over the fenestra ovalis. 



The parts of the membranous labyrinth (Fig. 985) are enclosed 

 by the bones of the auditory region : between the membranous 

 wall of the labyrinth and the surrounding bone is a small space 

 containing fluid, the perilymph. The labyrinth itself consists of 

 the utriculus with the three semicircular canals and the sacculus with 

 the cochlea (lagena). The utriculus (u.) is a cylindrical tube, bent 

 round at a sharp angle : the semi- 

 circular canals (ca., ce., cp.) are 



lod' 



FIG. 986. Male urinogenital organs of Lacerta 

 viridis. The ventral Vail of the cloaca is 

 removed, the bladder is turned to the ani- 

 mal's right, and the peritoneal covering of the 

 left testis and epididymis is dissected away. 

 bl. urinary bladder ; b. Ig. fold of peritoneum 

 supporting epididymis ; e/ 1 . anterior and cl z . 

 posterior divisions of the cloaca ; ep. epididy- 

 mis ; k. kidney ; mso. mesorchium ; p. copu- 

 latory organs, of which the right is shown 

 retracted (p') and the left everted (p) ; r. m. 

 retractor muscle of latter ; r. ridge separating 

 anterior and posterior divisions of cloaca ; 

 ret. rectum ; ret', its opening into the cloaca ; 

 t. testis ; u. g. urinogenital papilla and aper- 

 ture ; v. d. vas deferens. (From Parker's 

 Zootomy.) 



od 



FIG. 987. Female urinogenital organs 

 of Lacerta viridis. The ventral 

 wall of the cloaca, the urinary bladder, 

 the posterior end of the left oviduct, 

 and the peritoneal investment of the 

 left ovary and oviduct are removed. 

 b. Ig. broad ligament ; cl 1 . anterior 

 and cl 2 . posterior divisions of the 

 cloaca ; k. kidney ; mso. meso- 

 arium ; od. left oviduct ; od'. its peri- 

 toneal aperture ; od". aperture of 

 right oviduct into the cloaca ; ov. 

 ovary ; ur. aperture of ureter. (From 

 Parker's Zootomy.) 



arranged as in Vertebrates in general (p. 111). A narrow tube, the 

 ductus endolymphaticus, leads upwards towards the roof of the skull 

 and ends blindly in the dura mater. The sacculus is large and 

 rounded. The cochlea (I.) forms a flattened, not very prominent, 

 lobe, and is of simple form. 



