1908.] AXTECHIXOMYS AND OTPIER MARSUPIALS. 577 



a special mesentery not to be confused with the mesocolon, and 

 attaching it to the parietes of the right side of tlie body, there 

 is something of the same kind present. For the c?ecum of this 

 Semnojiithecus^ which is quite blunt at the apex, is fixed by a 

 membrane to the parietes in the inguinal region on the right 

 side. This had not the look of a former pathological adherence, 

 which would, I think, have presented a more iri-egular appearance. 

 There were of course no fixed loops in the colon. This special 

 attachment of the csecum is also found in some other Monkeys. 

 The general anatomy of the Squirrel Monkey, Chrysothrix 

 sciureus, has been desciibed by Martin *, who pointed out the 

 existence of an extremely short colon, which he found to be 

 only 65 inches in length. I can confirm this and add some 

 details which bear upon the subject of the present investigation. 

 The colon, rectum, and short ctecum presented ahnost exactly 

 the appearance of those viscera in a Viveiu-id, the large intestine 

 being slightly curved to the right, and thus shoAving as in many 

 Yiverrids a rudimentary transverse colon. It is an exaggeration 

 of the condition observable in Ateles ouelanochir, where the whole 

 of the colon is disposed in one bold curve rathei- more than 

 semicircular and precisely like that of Armadillos. In Ateles, 

 in fact, there is a well developed transverse colon, but hardly 

 an ascending colon. The whole gut appears at fii"st sight to be 

 suspended on a continuous mesentery, for it can be laid out in 

 a continuous curve either on the right or left side without 

 I'emoving it from the body, just as in such types. A closer 

 inspection, however, shows the presence of a ligamentuin cavo- 

 duodencde, so that the conditions obtaining in this Monkey ai'e 

 just like those which have been described above in the Carnivora. 

 This simplification can hardly be due to reduction in size. For 

 in the smaller Hcqxde iw/idcillata the gut cannot be turned over 

 freely to i-ight or left, and has the noi'mal syphon shape. 



Lemuroidea. 



The ansa coli of the Lemurs offers some particularly interesting 

 modifications. 



The simplest form of colon of those which I have examined 

 is shown in Microcehus smithii. Of this Lemur the general 

 anatomy has been described by Martin f. The colon shows no 

 special ansa or anscs, but is comparatively short and reaches 

 the terminal straight portion by a boldly curved tract in which 

 there are no permanent folds. This arrangement was identical 

 in two examples of the Lemur which I dissected. This is very 

 similar to the conditions figured in Cheirogaleus coquereli by 

 Dr. Mitchell, though I am not quite certain from his description 

 and figure taken together, whether there is or is not a well defined 

 colic looj) such as occurs in the genus Lemitr. Dr. Mitchell 

 speaks of "a colic loop .... relatively much shorter in Cheiro- 



* P. Z. S. 1833, p. 88. t P. Z. S. 1835, p. 125. 



37* 



