284 Tiio.MAs jiWK.iri' on- 



Class V. 



This class comprises seven spines, in each of which there is a ])raesacral too few, tlio 

 24th vertebra l)eing the fulcralis. In Group A. of tln-ee spines, a vertebra is wanting in 

 the lumbar x-egion. In B, of two spines, one is wanting in the back. In (Iroup C, con- 

 sisting of two very rare spines, there are 12 pairs of ribs, perfect at least on one side, and 

 only six ribless vertebrae in the neck. 



The spines are : Group A : D-7, 85, 377 ; Group B : 3.5(1, 478 ; Group C : 267, 202. 



Group A. 



D-7. Cat. 0370-20. 



Male, white, very old. C. 7, T. 12, L. 4, S. and C. 0. 



The spine is a very large one. The atlas is well shai)cd. luit was evidently co-ossified 

 with the occiput, though only a large fragment remains of bone i>artially filling the sockets 

 and rising above the anterior arch. It is i)robable that this is a pathological change, 

 occurring late in life. The 11th ribs are evidently very long, Init having been cut, the 

 length is unknown. The 12th pair are clearly rilis about 5 cm. long. The change of 

 articular processes, however, occurs above the last thoracic (10th), which has a decidedly 

 lumbar spinous process. The spread of the lumbar transverse processes is about the same 

 after the 1st. The 24th or 1st sacral vertebra is thoroughly, and nearly symmetrically, 

 sacralized. The promontory is above it, but there is a very slight false one below it. 

 The arch is thoroughly incorporated with the ne.xt vertebra. Thoiigli the line of de- 

 markation between this vertebra and the next below it in the auricular surfaces cannot be 

 made out, 1 feel justified in calling this the fii/cra/is. The auricular surface rests on three 

 vertebrae. The conjurjata vera is probably in the 3d, though there is a hint of it in the 

 4th also. There are six pieces in the sacrum, l)ut the last is probably the 1st coccygeal. 

 Below this there are three pieces of the coccyx, of which the upper is free and the two 

 lower fused. 



From the lOth, inclusive, downwards the spine is peculiar with a general blurring of 

 characteristics, and an increase of the transitional features. It was too much affected by 

 the changes of age to permit measurements. 



The theory of an undue advance of the ilium, and consequent (listui'l)ance of the 

 regular progress of development, would in this case offer a ver\' plausible explanation. 



