774 MR. ST. GEORGE MIVART ON THE [June 27, 



lines results, four points being directed forwards and three backwards 

 (fio-. 4, 1, 2, 3, 4). Of the four vertically superimposed cones of each 

 vertebra, the topmost one, or the dorsal lateral cone (fig. 4, i), 

 arises from the neural spine (iV.) and the zygapophysis (r.). The 

 cone next below, or the upper median lateral cone (fig. 4, 2), takes 

 origin also from the zygapophysis ; but below from the transverse 

 process or (hi more posterior caudal vertebrae) from the strong fascia 

 which takes its place (t.). The next cone below, or the lower me- 

 dian lateral cone (fig. 4, 3), arises from the same transverse process 

 or fascia and from the root of the inferior spinous process. The 

 lowest, or ventral lateral cone (fig. 4, 4), springs from (h) the infe- 

 rior spinous process itself. 



This arrangement continues forwards to about the fourteenth 

 caudal vertebra. Then the bases of the cones become excluded 

 from the articular processes and from the roots of the haemal spines 

 by the intrusion and backward prolongation of a supracaudal 

 muscular mass coming from the trunk (the sus-caudien externe of 

 Meckel, vol. v. p. 284), and by that of the femoro-caudal below 

 (fig. 5, S. C. and F. C.) ; so that the series of cones, being thus 

 modified, come to form a muscular sheath for these intruding muscles, 

 the sheath being strongly attached still to the ends of the transverse 

 processes and of the neural and hsemal spines. 



Fig. 5. 



Muscles of right half of a transverse vertical section of the tail at the seventh 

 caudal vertebra, showing the separation of the i-audal cones from the vertebra 

 by the intrusion of the supracaudal above and of the femoro-caudal below. 



A. Superior lateral caudal cones. B. Inferior lateral caudal cones. 

 F. C. Femoro-caudal. S. C. Supracaudal. 



The two series of median lateral cones more and more approxi- 

 mate as they approach the trunk, and, ultimately coalescing, are in- 

 serted strongly into the first caudal transverse process (fig. 15, x). 



The dorsal lateral cones, much modified, continue on as the lont/is- 

 simus dorsi. 



The ventral lateral cones terminate mainly by a very strong ten- 

 don implanted into the posterior end of the tuberosity of the ischium 

 (close to the origins of the two parts of the semimembranosus), a 

 portion, however, running on into a sphincter doacoe^m 



Of the intruding muscular masses the femoro-caudal, inserted into 

 the femur, extends for about one-sixth of the length of the tail, as 

 Meckel saysf, or to about the thirteenth caudal vertebra. 



* Meckel, he, cit. p. 285. t Loc. cif. p. 2SG. 



