CHARACTERS OF THE SOUTH AMERICAN MONKEYS. 107 



naked ano-genital area is tlie presence in II. jacchus of a number 

 of whitish pustules round the anus, on the perinseum and on the 

 ischial prominences. These exude under pressure a sebaceous 

 substance, which may be odoriferous. There is no trace of them 

 either in L. rosalia, in Mystax, or in (Edipomidas cedipus. (Text- 

 fig. 10, A-C.) 



In the Oebidse the ano-genital area varies considerably accord- 

 ing to the genus. In immature and unpaired females the urino- 

 genital orifice is a longer or shorter slit, above which, but 

 concealed from view by membi-ane (the hymen), lie the apertures 

 of the urethra and of the vagina. (Text-fig. 11, B, D.) 



In nearly all cases — that is to say, in Callicebus, Saimiris, Aotus, 

 Alouatta, and Cehus — the ischial prominences and the area between 

 the anal and genital orifices and above the anus are naked or 

 scantily hairy ; but in Lagothrix the hair grows tolerably thickly 

 and closely round the anus and genital area, covering the ischial 

 prominences and perinseum. 



In an adult, but unpaired, female Aotus the urino-genital 

 orifice is a very short and narrow slit bounded by small labia, but 

 there is no visible clitoris, the perinaeum and the area to the right 

 and left of the labia being somewhat swollen. The condition 

 observed resembles tolerably closely that of the Hapalidte. (Text- 

 fig. 10, D.) 



In an adult Gallicehus personatus (preserved in alcohol) the 

 perinpeum is comparatively short and the generative area is piri- 

 form, broad above, and naiTowed below, the orifice being flanked 

 by thickened labia inferiorly converging upon a small glans- 

 shaped, grooved clitoris, which is hardly, if at all, pendulous, A 

 young O. moloch resembles the last described, bvit the orifice 

 is merely a narrow slit, the thickened labia being undeveloped. 

 (Text-fig. 12, A, B.) 



In an immature Alouatta the rima is an elongated slit, wider 

 above than below and flanked by swollen labia. The clitoris 

 is short and subconical, with a slightly expanded apex. (Text- 

 fig. 11, B.) 



In an adult female Lagothrix the elongated rima is flanked by 

 a pair of much swollen labia, forming together an oval area nar- 

 rower below, where it passes into a, short subgiobular, ungrooved 

 clitoris, defined proximally by a constriction *. Lagothrix and 

 Aloicatta resemble one another tolerabl}'' closely in the structure 

 of the female external genitalia, (Text-fig. 11, A.) 



In an adult but unpaired female Saimiris the clitoris is long, 

 slender, pendulous, and grooved practically to the tip, which, 

 although tapering and not inci^assate, has a shield of thickened 

 integument on its anterior surface. (Text-fig. 10, E-G.) 



In Cehus the clitoris is elongated, slender, and grooved, prac- 

 tically to the apex as in Saimiris, but it is more penis-like, the 



* This specimen of Lagothrix had been injected for anatomical purposes, and 

 possibly the genitalia were abnormally turgid, owing to the injected preservative. 



