46 



back (as represented in the Zoological Journal, vol. ii. pi. xv.), the 

 muscles presenting comparatively few peculiarities, since the mo- 

 tion alluded to is remarkable rather for its extent, than the vigour 

 with which it is performed. 



" The principal elevators of the tail are the sacro-coccijgei-supe- 

 riores (sacro-sus-caudiens of Vicq d'Azyr). They arise from two 

 longitudinal ridges on the inferior and convex part of the sacrum, 

 and are inserted into the superior spines of the first six vertebrae by 

 detached tendons, terminating broadly in the anchylosed vertebrae. 

 The principal antagonists of these muscles, sacro-coccygei-inferiores 

 (sacro-sous-caudiens of Vicq d'Azyr), pass over the first five verte- 

 brae and terminate in the sixth and anchylosed vertebrae: their ori- 

 gins are wider apart than in the preceding pair of muscles, coming 

 off from the margins of the sacro-sciatic notches. In the interval 

 are situated small muscles passing from the transverse processes to 

 the inferior spines of the first six vertebrae. 



" From the limited nature of the lateral motions of the tail the 

 muscles appropriate to these movements are feeble, especially in 

 comparison with those which are observed in the birds that spread 

 their tail-feathers in flight, and in that way regulate their course 

 during that vigorous species of locomotion. . These muscles are in 

 number two on each side, arising from the posterior extremities of 

 the ischia and inserted into the expanded anchylosed vertebrce. 

 From the disposition of these muscles it is obvious that after the 

 proper elevators have raised the tail to a certain height, they also 

 become dorsad of the centre of motion, combine their forces with 

 the elevators, and by this addition of power terminate the act of 

 throwing up the tail by a jerk : so Mr. Vigors in his observations 

 on the living animal observes, that 'in these movements the tail 

 seemed to turn as if on a hinge that was operated on by a spring.' 



" The morbid appearances ohserved in this dissection were con- 

 fined to the alimentary canal, which exhibited in four places tracts 

 of inflammation of one and two inches in extent." 



The stuffed skin and skull of a Rodent Quadruped, brought from 

 Chili by Mr. H. Cuming, were laid upon the table, and characterized 

 by Mr. Bennett as forming a new genus, 



Octodon. 



Denies primores -§- acutati antice laeves j molares utrinque -£ era-^ 

 dicati complicati subsequales ; superiores subtransversi, facie antica 

 lata, postica ob incisuram externam profundam duplo angustiore, 

 interna medio uniplicata, plicis a primo ad postremum sensim mino- 

 ribus ; inferiores obliqui, singulo plica, externa internaque suboppo- 

 sitis coronidem in areas duas oblique transversales, figuram 8 vel 

 clepsydram quodammodo referentes, dispartientibus, plica externa 

 in postremo vix conspicua. 



Artus subaequales omnes pentadactj'li, digitis liberis, unguibus 

 falcularibus acutis. Cauda mediocris subannulata pilosa apice 

 floccosa. 



The teeth of this animal are remarkably different from those of 



