( 363 ) 



from these few facts that the state of the omentum will offer valuable generic and 

 famil}' differences in these animals. 



No less the mode of attachment of the intestinal canal by its mesenteries. 



In ('(tlUthrir they are (|uite simjile and nncomjilicated ; in Vt'rco]>ithecns, on tlie 

 other hand, there is nuich more complication. For example, in the latter form 

 the caecum has its own sheet of mesentery snsi)endiDg it to the dorsal parietes 

 quite independent of the main dorsal mesentery of the intestine. There is nothing 

 of the kind to lie noted in Cullithrix, whose caecum is not directly attached to 

 the parietes at all. It is obviously interesting to note the greater simplicity in the 

 New World monkey ; most persons hold that the Platyrrhines are of a more ancient 

 type than the Old World (!atarrhines. To other details of the arrangement of the 

 mesenteries I do not refer at present, as I have not compared them with other 

 genera and species. 



The intestinal canal of the species dissected by myself measures as follows : — 

 Small intestine 31 inches, large intestine 11^ inches, caecum 2^ inches. These 

 measurements are not widely different from those of C. -personafa, which were found 

 by Mr. Forbes to be : — .Small intestine A2,\ inches, large intestine 19 inches, and 

 caecum 2^ inches. In C. amicta, as recorded by the same naturalist, the measure- 

 ments were 42, 11^, and 2^ inches. Callithrix gigot is, according to Professor 

 Weldon, somewhat different in the proportions of the small and large intestines to 

 each other, and to the length of the body. The individual dissected by him was 

 of the same length as that dissected by myself, but the small intestine was 53 inches, 

 the large intestine 18, and the caecum about 2 inches. In C. rnoloch the same 

 author states that the small intestine was 35 inches, the large intestine 19 inches. 

 On the whole, however, it may be stated that CalUthnx is to be characterised by 

 the shortness of tlie intestinal canal as a whole, and by the proportionately long 

 large intestine. Some tables of comparative measurements are given by Forbes 

 in the memoir quoted, from which it appears that Brachjurus has the longest 

 intestine, and that other genera may be placed thus in descending order : — Ateles, 

 Pitkecia, Cebtis Callithrix, Ni/ctijiitlieci(.'<. CdUithrix in this particular is decidedly 

 nearest to Nijctipithecus. The small intestine presents no noteworthy characters. 

 The Caecum is not exactly like that of either C. gigot or C. moloch. It lies straight 

 without bend or coil, and has no dilatation at the extremity. In C. persoixita Mr. 

 Forbes states that the caecum is coiled on itself The caecum is attached to the 

 small intestine by a median anangious fold, which extends on to that intestine for 

 a distance of about two inches. Besides this there arise from the large intestine 

 two bloodvessel-bearing folds which are attached laterally to the caecum, but 

 which, especially on one side, are not conspicuous. The folds are not in any way 

 united to each other. The conditions of the eaecal frenum and other mesenteries 

 exhibit considerable variations among the Primates. 



I pointed out myself some years since that in two species of Callithrix * the 

 median frenum appeared to be supplied with a blood-vessel, since the lateral caeco- 

 colic mesentery joined the median iieo-caecal fold. The matter has been dealt witli 

 in a large number of forms by Sir William Flower in his well-known contribution f 

 to the strncture of the alimentary canal in Mammals. I may observe in accordance 

 with what Flower has described that in Ateles mclanochir the arrangement of the 

 eaecal mesenteries is precisely that of ('allithrix tonpiata ; the median frenum bore 



* " Notes on Brarhi/iinix ralviix^" P.Z.S., 1887, p. 120. I li.ive no not« as to the xprcies. 

 t Med., Timt's aii<l (la-.ittr, 1872. 



