PERITONEUM OF MAMMALIA. 



501 



388 



the splenic covering. Both layers recede to include the stomach, 

 fig. 388, b, whence they are continued from the line of the greater 

 curvature over the fore part of the abdomen, and are folded back 

 to the colon, in the form of a large flap or apron, including vessels 

 and more or less fat, forming the ' great omentum,' ib. o, o : it is 

 peculiar to the Mammalia, coexists with the diaphragm, and may 

 have useful relations as insulating the peristaltically winding in- 

 testines from the constant respiratory movements of the abdominal 

 walls. The posterior returning folds of the omentum meet 

 the transverse arch of the colon, recede and embrace that intestine, 

 as the anterior or descending folds had embraced the stomach ; 

 the colonic folds are continued 

 back as a suspensory ( meso- 

 colon ; ' the upper layer of the 

 fold passes over the fore part 

 of the duodenum and pancreas 

 to the posterior abdominal 

 walls, the lower layer is con- 

 tinued a short way down those 

 walls, and is again reflected 

 forward to the small intestines 

 as the anterior or upper layer 

 of their suspending fold called 

 ( mesentery.' The relations of 

 the peritoneum to the pel vie vis- 

 cera show no class-specialities. 

 Large omental processes with 

 accumulated fat are never con- 

 tinued from the urinary blad- 

 der, and rarely from the pelvic 

 or other regions of the abdo- 

 minal walls, as they are in most 

 Reptilia : l small ones from the 

 serous coat of the large intes- 

 tine are developed in many Ungulates, and are called ' appen- 

 dices epiploicae ' in the human subject. The serous sac of the 

 abdomen communicates with the mucous canal of the oviducts or 

 ( fallopian tubes,' but is elsewhere closed in the female, and is a 

 shut sac in the male mammal. Productions of this sac, how- 

 ever, accompany the testes into the scrotum ; but are insulated 

 by obliteration of the canal of the spermatic cord in Man. 



The above leading features in the disposition of the peritoneum 

 offer modifications in the present class. In the insectivorous 



1 xx. vol. iii. pt. ii. p. 221. 



Liver raised to show the stomach and great 

 omeutum, Human. CXLVIII". 



