REPORT ON THE SPHENISCID^. 189 



communicate freely with one another. The anterior compartment is continuous with the 

 rectum, and receives the fseces, while the posterior compartment, separated from the 

 anterior by the fold above described, forms a sort of transversely elongated diverticulum 

 or cul-de-sac, into the blind extremity of which open the ducts of the urinary and genital 

 organs. The apertures of all these ducts in the male (PI. XVII. fig. 7) are situated on the 

 extremities of nipple-shaped eminences. In the female (PI. XVII. fig. 8), on the other 

 hand, these eminences are only three in number, and of these two are of larger size than 

 the third. The two larger correspond, as in the male, to the openings of the ureters, while 

 the smaller papilla, which is not provided with any aperture, indicates the position of 

 the extremity of the right or aborted oviduct. The oviduct of the left side communicates 

 by means of a narrow aperture with the uro-genital cul-de-sac, and is not provided with 

 any papillary eminence. 



Behind the globular cloaca the gut diminishes in size, to form the anal passage, which 

 opens externally at the anus. The mucous membrane of this portion of the gut is 

 thrown into longitudinally arranged rugae. Between the cloaca and the anal passage 

 is a transversely placed fold of mucous membrane, which is limited to the upper 

 Avail of the passage. This fold separates the apertures of the urinary and genital 

 ducts in front from that of the bursa fabricii behind. The modifications presented by the 

 bursa fabricii in difi'erent species I shall describe presently. Meanwhile, I may observe 

 that its aperture of communication with the anal passage presents the form of a trans- 

 versely elongated slit, and is not defended by any valve. 



The description above given of the interior of the cloaca, shows that the Penguins 

 agree with the majority of birds in so far as the structure of this portion of the gut is 

 concerned. Mr. W. Forbes,^ in an instructive paper on the bursa fabricii in birds, shows 

 that in the great majority (excepting the Struthionidaj) the cloaca is divisible into 

 three distinct* chambers, which correspond respectively to the rectal, urino-genital, and 

 anal passages above described. The position of the terminations of the urinary and 

 genital ducts, as well as of the aperture of the bursa fabricii, he found to be similar in 

 the very numerous species which he examined. The accuracy of these observations 

 I have now been able to confirm in respect of every species of Penguin which I have 

 examined. 



The anal passage is provided with three muscles, two levatores and a sphincter. 



The levatores ani (PI. XVII. fig. 6) are two riband-Hke muscular bands, described by 

 Gervais and Alix ^ under the name of " releveurs de I'anus." Each arises from the posterior 

 border of the ischium, close to the posterior or free extremity of the pubic bone, and 

 passes backwards to be inserted into the lateral surface of the anal passage, and 

 to a small extent into the posterior wall of the globular cloaca. Each of these muscles, 



1 On the Bursa Fabricii in Birds, Proc. Zool. Soo. Lond., 1877, p. 304. 



2 Osttiologie et Myologie des Mauchots, p. 16. 



