218 DR. p. CHALMERS MITCHELL ON THE 



ingenious method of figuring the spiral. He selects what he 

 takes to be the apex of the loop, and up to this point tints the 

 entering limb of the intestine black, leaving the limb of exit 

 from the apex outwards round the spiral in grey (Lonnbei\g, 

 1907, fig. 4). Dr. Beddard has adopted Lonnberg's method and 

 has carried it further. In a, set of diagrams (Beddard, 1909, 

 text-fig. 13) he represents the colic spirals of six animals and 

 arranges them in two series, each series indicating what he 

 describes as a distinct type of spiral. In each case he has 

 selected what he takes to be the apex of the loop, and, like 

 Lonnberg. shades the entering limb bla,ck, the limb of exit grey. 

 In one series, containing Madoqua 2'>hillips\., Cejiihaloph^is dorscdiSy 

 and Moschus moschlferus, the entering limb of the intestine is on 

 the smaller curve of the spiral as it approaches the apex, and if 

 the apex happens to point towards the end of the long axis of 

 the spira,l, away from the point of entrance, then the entering 

 limb finishes on the csecal side of the apex. In the second seides, 

 containing Tragulus stanleyanus, Cejjhalo])}^.? maxivelli, and 

 Aoitilocapra americana, the entering limb of the intestine lies on 

 the larger curve of the spiral as it approaches the apex, and if 

 the apex happens to lie towards the end of the long axis of the 

 spiral away from the j)oint of entrance, or be imagined to have 

 grown round to that point, then the entering limb finishes on 

 the opposite side of the apex from what hajDpens in the first 

 type. This distinction between the types of spiral is stated by 

 Dr. Beddard to be so important that the presence of one type in' 

 one species of Cejjhalophtcs, and of the other in another species 

 of that genus, is a generic distinction, confirming certain 

 undesignated difiei'ences in external characters which " appear 

 to him to be quite as great as those which distinguish certain 

 other ii;enera. of Antelope." 



It is plain, however, that the i-eality of the distinction on 

 which Dr. Beddard relies, depends on the actual point selected 

 as the apex of the spiral. In text-fig. 19 I have reproduced 

 the drawings which Dr. Beddard gives as the first examples of 

 each type (Beddard. 1909, text-fig. "l 3, 1, 2), with the altei^ation 

 that they ai-e revei'se'l as in a mirroi-, to make easier comparison 

 with Dr. Lonnberg's figure (Lonnberg, 1907, fig. 4) and my own 

 diagrams, and with an addition to which I shall refer presently. 



Obviously, if Dr. Beddard had continued the black shading- 

 representing the ingoing limb of the intestine from the point 

 marked X, where he left it in the figure of Tragulus, to the 

 point I have marked XX in the same figure, the two '' types " 

 of spiral would have been in every way identical. Anyone who 

 has a.ttempted to follow the closely adpressed limbs of a. compli- 

 cated ruminant spir-al on the actual specimen, will appreciate 

 that the fixing of the actual apex is a difiicult judgment and not 

 a, substantial basis for the discrimination of types or the deter- 

 mination of genera. ' The judgment is the more difiicult, because, 

 as I have already explained, any two contiguous portions of the 



