THE GENERATIVE APPARATUS OF BIRDS. 889 



mnjora; the other mucous, the labia minora (or nymphx). The lahin majora are 

 rnally, continuous alwvc with the mons Venn-is, and unite In-low to form an 

 acute angle, name I tin- fniiri-Jit'tte; tliey are covered externally with hair. The A ('>/< 

 lithium, more or less developed, leave the tburchctt. , nml extend around the entrance to 

 tin- v.igina. uniting above the clitoris, and forming the prepuce uf that oru' m. 



The clitoris is lodged in the superior commissure of the vulva; its {mint is directed 

 downwards, especially during erection; its base is attached, on each side, to the two 

 i-reciile lobes which constitute the bull) of t^e vagina (btilhi vestibuli). 



Two racemose glands, the vulvo-vayinal or glanils of Bartholine, pour their secretion 

 over the walls uf the ve.stilnde. 



Mitmiiw. These are pectoral, and two in number. In their centre, they present an 

 enormous papilla the nipple into which the excretory canals open ; it ia surrounded by 

 n brown circle, the anolaofthe nijiple. 



CHAPTER III. 



GENERATIVE APPARATUS OF BIRDS. 



1. Male Generative Organs. 



THE generative organs of the male are the testicles, and an excretory apparatus much 

 simpler than t h it of mammals. 



'. These organs are placed in the sublumbar region of the abdominal cavity, 

 behind the lungs, and below the anterior extremity of the kidneys. Their form is 

 usually oval, and their volume varies with the different species, as well as at different 

 seasons ; at the breeding season they are greatly developed. 



Excretory Apparatus. In birds there is not, properly speaking, any epididymis. The 

 vas deferens passes from within the posterior extremity of the testicle, is directed in a 

 flexuous manner backwards, draws near to the ureter on its own side, going along the 

 kidney with it, and arriving at the cloaca, where it terminates by an orifice to be alluded 

 to hereafter. In the Duck, it has near its termination a small oval vesicle, always filled 

 with spermatic fluid. 



Organ of Copulation. This varies with the species. In the Gattinaae, it is only 

 a small papilla placed below, near the margin of the cloacal opening, and between the 

 two orifices of the deferent canals. This papilla is traversed by a furrow through which 

 the semen flows. In tli" PalnfoadM, this organ is much more developed, and is 

 peculiar. Contained within a tubnlnr cavity in the cloaca, it is protruded externally at 

 tlie moment of copulation by the eversion of this cavity, like a finger out of a glove ; it 

 then appears as a long pendant appendage, twisted like a cork-screw. 



2. Generative Organs of the Female. 



The development of the young animal taking place external to the female, the 

 generative organs are limited to that producing the ovum, and the duct through which it 

 passes on leaving the ovary. 



(trunj.- In birds there is only one ovary, which is situated on the left side, the right 

 one becoming atrophied very early in nearly all specie*. This ovary is situated, like the 

 '*, in the sublumbar re-ion ,,t the abdominal cavity, and constitutes a more or less 

 voluminous body, composed of a variable number of ovule.-, in pn>c. .-.- of d. v< 1'yment : 

 some very young, little, and white; others m..n- advanced in age, being larger and 

 yellow in colour. The ova are enveloped in a very vascular cellular membrane, whi>-h, 

 when they are ripe, splits in a circular manner, following an equatorial line, and permits 

 IJM- of the essential part of the nrg the i/,ll,,,r (;///.). or ritfllu*. 

 lift. This duet is long, very wid. ami dilatable, and very !! .\uous. It begins, 

 nenr the ovary, by an miffing, d ]>avil on. and t. rmin.ite-. in the el.-aea by a un< 

 narrow orifice, which ia eon.-iderab y widened when the egg passes through it. The egg, 

 com | H wed, on entering the oviduct, of tin- fundamental pnrt named the yelk, or rit'lhu, is 

 envelojM-d in an albuminous >ph. -re dining iis p . ards the cloaca, and 



with a pro I* etiii'_' >hell. The o\iduet of birds ix. tin : thing more than 



an excretory canal, as it participates in the formation of the ovum. It is coinpn.- 

 three membranes: an istiriutl seroius maintains the tortuous till*-; u miildtt, muscular; 

 and un ititt-riinl. mucous. 



