NUMERICAL VARIATION IN THE HUMAN SPINE. 



283 



141. 



ticularly interesting ccjn.sidered in connection with that of tlie preceding spine. Tt is very 

 thoroughly sacrulized. The promontory is ahovo it. Below it is a faint secondary promon- 

 tory with a very slight remnant of connective tissue in the middle. The latei'al masses are 

 well developed and nearly symmetrical. It is very hard to 

 decide just how much of the auricular surfaces they form ; but 

 the left half of tliis vertchra forms so large a part of it as to 

 make it very possibly the J)i/cr(i/ls, at least on that side. On 

 the rio'ht it forms a smaller |)ortion of the surface and is not the 

 fnlcrafis. ( )n the back there is a large interval l)etween the 

 arch and that of the next vertebra. Though there nuiy ))e co- 

 ossiHcation at the articidar processes, there seems no doubt that 

 once there were true joints. Another reason for calling this 

 vertebra lumbar is that in that case the coiijugnfa rem passes 

 through the 3d sacral. The C(;ccyx itself is of an uncertain 

 number of elements. The last sacral is I'atlier transitional. It 

 is curious that while with this spine there is more doubt which 

 vertebra is the fn/cral is t\mn liicre was with tlie last, yet the arch of tlie doubtful vertebra 

 in the preceding spine is much moi'e incorporated with the sacrum than in this one. 



There are several spines in this Class in which one is much tempted to call the 24th 

 vertebra the fukraJis, but I have adhered rigidly to the definition that the fidcrd/in is the 

 one that forms the largest part of the auricidar surface of the sacrum. In some of these 

 this may be true of the 24tii on one side. The greatest objection to the theory of the /'»/- 

 era/is is that (iiowever this matter of the auricular surface may be) the 24th is practically 

 a part of the sacrum, and that if the free portion of the spine is to be considered as an ap- 

 paratus, the 24th must be left out of it, although it be not the fii/cra/is. It is also certain 

 that in several of these spines there is a very transitional arrangement at the junction of 

 the lumbar and sacral regions. The difficulty is a sex'ious one; and should be frankly ad- 

 mitted. I was at one time disposed to reject the fulcraVis on tliis account. The fact that 

 instead of a certain vertebra we sometimes find one or more transitional ones, does not 

 force us to deny the existence of that vertebra in a particular form in the innuense major- 

 ity of cases. 



It must be admitted tfiat tlie specimens in Grou[) I) of this Class tall}- very well with 

 Rosenberg's view. The fact that tlie 23d so often has the features of a penultimate lum- 

 bar seems to me to sj)eak for this interpretation, for T do not see how the assumption of 

 sacral characters by the 24th, in the absence of a vital principle, can affect the details of 

 the transverse processes of the 23d. 



More difficult cases to account for in this way are found in the next class. 



