OF NATURAL HISTORY. 8S 



The ftruclure of the her.rt, in granivorous birds, is nearly 

 the fame with that of quadrupeds. 



The lungs hang not loofe in the cavity of the thorax, but 

 are fixed to the back-bone : Neither are they divided into 

 lobes, as in man and other animals whofe fpines admit of 

 confiderable motion. They are red, fpongy bodies, covered 

 with a membrane that is pervious, and communicates with 

 the large veficles or air-bags which are fpread over the whole 

 abdom.en. Thefe velicles, when diftended with air, render 

 the bodies of birds fpecifically light. They likewife fupply 

 the place of a diaphragm, and ftrong abdominal mufcles. 

 They produce the fame effefls on the vifcera as thefe muf- 

 cles would have done, without the inconveniency of giving 

 an additional w^eight to the body. 



Birds have no bladder of urine : But a blueifh-coloured 

 canal, or ureter, is fent off from each kidney, and terminates 

 in the recSlum. Their urine is difcharged along with the 

 faeces. It is a v/hitifh fubftance, and turns chalky when ex- 

 pofed to the air. 



The tefticles of the male are fituated on each fide of the 

 back-bone, and are very large in proportion to the fize of the 

 animal. From the tefi:icies proceed two feminal duels, 

 which at firft are ftraight, but afterv/ards acquire a convolut- 

 ed form, as in the epidydymus of man. Thefe du«^s termi- 

 nate In the penis, of which the cock has too, one on each 

 fide of the common cloaca. They are very fmall and fhort 5 

 and, from this circumftance, they long efcaped the notice of 

 anatomiils. 



In the female, the clufi:er of yolks, being analogous to the 

 human ovaria, are attached tg the back-bone by a membrane. 

 This membrane is very thin, and continues down to the 

 Uterus. The yolk, after feparating from its fiialk, pafl^es into 

 a canal called the infundibulum, where it receives a gelatinous 

 liquor, which, with what it farther acquires in the uterus,, 



