26 STUDIES IN TASMANIAN MAMMALS, LIVING AND EXTINCT, 



of the Kgamentum nuchae, as is usual among animals with 

 heads carried horizontally, left this part of the spine 

 free for the needs of the special adaptation that wa find 

 to obtain. Some kind of pad must have existed between 

 these two spines, either muscular, cartilaginous, or liga- 

 mentous, but in the macerated bones the slightest com- 

 pression of the cervical series, as a whole, jams the two 

 spines firmly together. This special adaptation is, as far 

 as we know, unique. In a monograph upon Nototherium 

 tasmanicum, this action of the two anterior cervical spines 

 in Nototheria was noted in the following terms : — ''During 

 "normal vertebral articulation, the aborted spine of the 

 ''atlas worked against this point in the axis, both being 

 "flattened and roughened, as if for a loose kind of syndes- 

 "jiiosa! union." ( 20 ) 



The posterior edges of the atlantean neurapophyses 

 are groove-scarred for 35 mm. on cither side, to receive 

 intsrspinalis muscles, and ligaments that filled a. fossa in 

 the atlas 40 mm. wide x 40 mm. high; indeed, the whole 

 under portion of that spine is thus excavated. This bold 

 excavation of the neurapophyses continues throughout the 

 cervical series, and when the rev: nib is reached, in spite 

 of its apparent thinness, it yet yields a muscular and liga- 

 mentous attachment fossa, 70 mm. wide and 20 mm. 

 deep. 



This enormous padding of muscles and ligaments, 

 added to the great strength of the zygapophyses, enabled 

 what would otherwise be a weak neck to withstand enor- 

 mous shocks, and was a special evolution cf the marsupial 

 ton. To give stress to this point it may just be 

 added that the fourth cervical is only 34 mm. thick, 

 measured through the centrum, but the processes for 

 interlocking bring its total up to 65 mm. 



The vertebra-artereal foramina are completed by 

 bone in the third and subsequent vertebrae ; are nearly 

 completed in the axis, and indicated only in the atlas; 

 the sizes of these are given in the table of measurements 

 appended hereto. In the specimen under examination, 

 the right diapophyses is complete, and the left nearly so, 

 the former enabling us to say that the muscular attach- 

 ments were a.ll of a very extensive character. Skullwards 

 the homoloffue of the rectus capitis lateralis, and the 

 superior oblique claimed large areas, while the scar upon 

 the back of the process evidently related to a moiety of 

 the levator anguii scapulae. The similarity cf such 

 muscles as the latter, with those of man, related in part 

 at least to the complete revolution of the arm in mar- 



