IGUANA TUBERCULATA. 367 



along this surface runs the ureter, which is collecting its branches as it 

 passes backwards, or nearer to the anus [cloaca], where it terminates 

 in a ridge just by the termination of the vasa deferential In the 

 ureters, from the animal whence this description was taken, were 

 calculi, or rather one calculus in each, of a brown colour, almost filling up 

 the duct. 



What appears from its situation to be the vesica urinaria is an oblong 

 bag, large, and opens into the termination of the rectum and beginning 

 of the anus by a very large opening : it was filled with a white fluid 

 like milk ; there were some small calculi in this, of a white colour. Is 

 this the bladder of urine ? If it is, then the urine must pass across the 

 anus to it. I did not find any white fluid in the ureter ; nor was the 

 calculus, formed in each, of the same colour ; nor did this bladder appear 

 to be glandular in its coats, so as to be able to secrete the white fluid 

 contained in it. 



The Organ of Hearing. — The tympanum is a large cavity, immedi- 

 ately on the inside of the membrane, along which passes the bone of 

 the ear. The Eustachian tube is a very large passage from the mouth 

 or fauces, to the cavity of the tympanum ; it is oblong at its beginning ; 

 its longest axis being in the direction of the mouth and fauces. This 

 passage is short and passes almost directly outwards, and enters the 

 tympanum by nearly as large an opening as at the beginning : it is 

 lined with a thin dark membrane ; there seemed to be no cartilaginous 

 part 2 . From the membrana tympani there passes inwards, through 

 the cavity of the tympanum, a small bone which is attached to the upper 

 part of the tympanum, making a ridge there ; its length is equal to the 

 depth of the tympanum. The bony vestibulum is a small cavity having 

 the three semicircular canals, going out much as in the human subject, 

 viz. two perpendicular, and one horizontal. The bony vestibulum and 

 semicircular canals are lined, or rather contain a kind of gristly sub- 

 stance, which makes a cartilaginous vestibulum and semicircular canals. 

 "Within this last-mentioned vestibulum is a small white body something 

 the shape of a lens ; this is a calcareous earth of the consistence of 

 powder of chalk wetted and dried ; rather harder than that which is in 

 the turtle's ear 3 . 



1 [Hunt. Prep. Phys. Series, No. 746. The male organs are shown in Hunt. Prep. 

 No. 2434: the female organs in No. 2717.] 



2 [See Dissection of the Turtle, p. 355.] 



3 [Hunt. Prep. Phys. Series, No. 1576. The tongue and sublingual pouch are 

 shown in the Hunt. Prep. No. 1457.] 



