Macalister — On two Forms of PerityphUc Pouches. 217 



tlie lower ribs were Ibent inwards ; there was a compressed stomach, a 

 very characteristic schnurleher whose right end reached nearly to the 

 crest of the ilium. This vicious habit forcing the viscera downwards 

 evidently exaggerated, if it did not cause, the disposition of the colon 

 to burrow behind the psoas muscle, and thus to produce this fossa. It 

 is interesting also to note that one of Biesiadecki's cases was also a female, 

 while in Leeper's the pouch was utterly unconnected with any cascal 

 relation. 



The other instance was of less interest, though more complex. 

 In an old, tliin female, which happened to be on the next table in the 

 dissecting-room to the case just cited, the caecum had just reached the 

 iliac fossa, and, consequently, was well covered with peritoneum, and 

 its fundus had just begun to turn forward when its growth was arrested; 

 hence the vermiform appendix hung inwards and a little forwards 

 below, but not in front of the opening of the ilium. A strong ligament 

 of Hensing passed from the csecum to the abdominal wall, forming the 

 outer boundary of a sub-csecal sac, in which the fundus of the csecum 

 lay, and which its sharp falciform border rendered very deep and dis- 

 tinct. The mesenteriolum had not yet reached its usual perfect 

 distinctness, but the appendix lay in a distinct peritoneal fold, at 

 the bottom of the sub-csecal fossa, whose cavity it divided into an inner 

 and outer part, the former having a shallow digital recess from its 

 floor under the ilium, and its separation from the outer was completed 

 by a ridge passing from the mesenteriolum to the anterior and inferior 

 part of the abdominal wall, as represented in the figure. The interest 

 of this case is, that it shows a primary stage of both the sub-caecal and 

 inferior ilio-csecal fossa, in which the two are confluent, for the sac in 

 this instance is really a sub-csecal one with an imperfect septum. A 

 further descent of the csecum would have been attended with an in- 

 creasing prominence of the vermiform appendix, and an increasing 

 distinctness of the mesenteriolum, then the inner fossa would 

 form a perfect ilio-csecal recess, while the outer would be a sub-csecal 

 fossa. The continued descent of the csecum, however, would have the 

 effect of obliterating the sub-csecal fossa, and leaving then the ilio- 

 csecal alone. The resemblance between this case and that of Waldeyer 

 is so close as to lead me to believe that they are both varieties of one 

 species ; and the comparison of these with the other cases throws a clear 

 light on the genesis of these peculiar and often dangerous pouches.*^' 



* Since this paper -was written (June, 1876) an instance has come under my 

 tiotice of a very peculiar additional variety of sub-csecal fossa. In a male adult, 

 aged about sixty, a narroAV slit-like opening was found below and in front of the 

 cfecum, about 1^" long, and starting below the ilium, and extending transversely; 

 on introducing the finger it passed under and behind the caecum, and the fundus of 

 the pouch was found placed upwards, backwards, and outwards, on the level of the 

 crest of the iHum. The cajcum thus lay in and bounded this fossa, in the floor of 

 which was the vermiform appendix. The formation of such a pit was probably 

 due to the occurrence of an adhesion between the layers of the peritoneum and the 

 back of the cascum, while the latter was descending ; so that the intestines, in pass- 

 ing down, instead of separating the laminaj, aa usual, left this portion behind it. 



E. I. A. PEOCi, SEE. li., VOL, II. j SGIEXCE, 2 G 



