CHAP, in.] VERTEBRAE AND RIBS : GORILLA. 117 



Jahrb., I. p. 160. Tables, Xote 19. This case therefore shews forward 

 Homceosis in the presence of ribs on the 21st, also in the transitional 

 character of the 25th, together with increase in total number. This 

 increase is however not always found when the 25th is lumbo-sacral, 

 for, on the contrary one such case quoted by Rosenberg had only 

 4 caudals (q.v.). 



In this form the number of vertebrae articulating with the ilium 

 varies, and the number uniting with the sacrum is also liable to 

 alterations probably connected with age. Rosenberg, I. c. : Cat. Coll. 

 Surg., 1884, n. p. 3. 



Gorilla savagii. C 7, D 13, occur in all skeletons of which I 

 have fouud descriptions, making therefore one pair of ribs more 

 than in Man 1 . 



The number of vertebrae articulating with the ilium and the 

 number joining with the sacrum vary, perhaps with age. Cf. 

 Rosenberg, I.e.; Cat. Coll. Surg.; Struthers, J. Anat. Phys., 1875, 

 p. 79 note, &c. 

 '35. Adult female. C 7, D 12, L 4, S 5, C 3. This is a remarkable 

 case. There is one rib-bearing vertebra less than usual, while the 

 number of lumbo-sacrals is nine, as in the normal cases collected 

 by Rosenberg. In a normal skeleton in the Camb. Mus. the 

 articular processes change from the dorsal to the lumbar type 

 between the 20th and 21st, but in this abnormal specimen the 

 change is completed on the right side between the 19th and 20th 

 as in Man, and on the left side, though the change has there also 

 taken place, there is a curious irregularity in the fact that the 

 posterior zygapophysis of the 19th is divided to form two processes 

 which fit into two similar processes of the left anterior zygapo- 

 physis of the 20th vertebra. The rest is normal. Cambridge Univ. 

 Mas., 1161, F. [There is here, therefore, a backward Homceosis of 

 all vertebras from the 1 9th onwards ; perhaps also an absolute 

 diminution in the total number of segments. The simultaneous 

 variation of both the number of ribs and the position of the 



1 Since this account was written, Struthers has published a valuable paper 

 (Journ. Anat. Phys., 1892, xxvn. p. 131), giving particulars of twenty Gorilla 

 skeletons. Of these the following are especially remarkable. 



Female, C 8, D 13, L 3. The seventh cervical is formed like a sixth, and the eighth 

 is formed as a seventh, bearing no rib. The vertebrae 9 to 21 bear ribs, those of tbe 

 21st being well formed and coming close to iliac crest. The change of articular 

 processes from dorsal to lumbar type occurred between 21st and 22nd, namely, one 

 vertebra lower than usual. There is thus a forward Homceosis in absence of ribs on 

 8th, in presence of ribs on 21st, and in the variation of position of the articular 

 change. 



Out of 20 skeletons 3 have 14 pairs of ribs (on 8th to 21st) instead of 13 pairs. 

 In one of these the articular change also occurred one vertebra lower than usual. 

 On p. 136 a case is described in which there was a remarkable asymmetry in the 

 structure of the articular processes, which as Dr Struthers has pointed out to me, is 

 in some respects like that here described as No. 35 in the text. 



Struthers points out that it would be better in all cases to speak of the change of 

 processes as from lumbar to dorsal instead of from dorsal to lumbar. I regret that 

 this suggestion comes too late for me to adopt. 



