G18 Mr. A. Cabrera on the 



Thunberg et de Delalande, sont tellement intimes, qu'ayant 

 sous les yeux, d'un cote, l'e'tat adulte du premier, sans son 

 jeune &ge, et, de I'autre, le tres jeune age de la seconde sans 

 son etat adulte, on devait etre porte a attribuer a de simples 

 differences d'&ge les differences que Yon apercevait entre le 

 pelage de Fune et celui de I'autre. M. Fre"de"ric Cuvier 

 n'hesita done pas a les reunir, et e'est par suite de cette con- 

 fusion qu/il donna l'Afrique australe pour patrie au C. pyg- 

 erythrus: espece n'ayant en realite pour type qu'un individu, 

 achete de marchands qui ignoraient entierement son origine, 

 et dont la veritable patrie reste aujourd'hui ra^rae inconnue." 



I. Geoffroy, who saw the type of pygerythrus and compared 

 it with adult specimens of the grey form collected by Verreaux 

 in South Africa, emphasized the difference between them in 

 his " Synopsis " included in the same book (pp. 19-34), 

 describing the Cuvier species as very distinct from the Cape 

 one "par son pelage vert jauna-tre et non gris." 



We must, consequently, leave the name pygerythrus for a 

 red-vented Cercopilhecus with green fur, the typical habitat 

 of which is unknown, and adopt another for the grey-coloured 

 form found in South Africa. Desmoulins, who suspected 

 before Geoffroy the distinction between them, calls the latter 

 C. pusillus, attributing this name to Delalande*. Unfor- 

 tunately the name of the French traveller appeared, no doubt 

 accidentally, italicized like that of the animal, thus: " Cerco- 

 pithecus pusillus Delalande" ; and it was on account of this 

 that I. Geoffroy considered the term a non-binomial one and 

 rejected it, calling the species C. lalandii. Mr. Oldfield 

 Thomas, to whom I applied for his opinion on the subject, 

 thinks the apparently uncorrect name is a printer's fault, 

 as the whole article in which it appeared is written in con- 

 formity with the principles of binomial nomenclature ; and 

 I entirely agree with his decision. We must therefore call 

 the South-African monkey C. pusillus. 



Long before the publication of this name, as early, in fact, 

 as in 1811, the same animal was mentioned by Lichtenstein 

 as C. glaucus; but no description being given, this name is 

 merely a nomen nudum. 



Now, if we consider all the Cercopitheci with red vent 

 local forms of a single species, the green one, beino- 

 described the first, will be typical, and C. pusillus will be- 

 come C. pygerythrus pusillus. As for the true pygerythrus, 

 1 think it can be identified with one of the green subspecies. 



* Dictionn. Class, d'llist. Nat. vii. (1825) p. 568. 



