DE. J. MUEIE ON THE FORM AND STRUCTURE OF THE MANATEE. 137 



my first impression. I may further say that of very many skeletons, in various stages 

 of growth, examined by me in Continental and English Museums, none exhibited more 

 than six cervicals. 



As to the second point, recognition of the absent one, De Blainville took up the 

 question very categorically, inasmuch as he maintained that in one of the Leyden speci- 

 mens he counted seven ; and he assumes rather than proves that " la sixieme, finit par 

 disparaitre dans son corps ; Tare restant libre dans les chairs, est enleve avec elles." 

 This statement has been contradicted by Vrolik, who cites Temminck, Schlegel, and 

 Peters as witnesses in evidence of its absence in the Leyden skeleton in question. In 

 my examination of the same specimen I certainly only found six. Professor Brandt also 

 throws doubts on De Blainville's assertion ; and he himself, in a study of the Sirenian 

 neck-vertebi'se, holds, from analogy in the disposition of the cervicals of Halicore and 

 Mhytina, and the way in which the head of the first rib articulates, that the seventh is 

 that which is wanting. The first dorsal, however, or numerically the seventh from the 

 cranium, he is inclined to regard in the light of an anomaly — functionally a dorsal, yet 

 in some way a cervical. Somewhat incongruously I think, while admitting on sound 

 grounds but six for the neck, he would do away with this apparent exception by the less 

 stable assumption of a cervical simulating an undoubted true dorsal. Professor Flower, 

 in a short communication', very sensibly argues against Brandt's opinion. Basing his 

 reasoning oh the cervical irregularity extant in the Sloth, as elucidated by Bell and 

 Turner, and on the individual characters of the seven cervical vertebrae of the Dugong 

 compared with those of the Manatee, he concludes that morphologically the sixth is 

 the missing one in the latter animal. 



For my own part I venture to dissent from the above distinguished authorities ; and 

 suggest that it is the usual third cervical of Mammals which is the undeveloped or 

 absent one in Manatus. This con\'iction I am led to adopt for several reasons. In 

 Cetacea with ankylosed cervicals more generally the third is the least distinct, the 

 fourth, fifth, and sixth by degrees e^dncing greater separation. In adult Sirenia 

 occasionally the axis and so-called third and fourth are found partially united. In 

 them also the three vertebrae succeeding the axis, although subequal in thickness, do 

 show slight successive increment, so that, ceteris paribus, the missing true third one 

 would be most reduced, and its thinned body and lamina more readily coalesced to non- 

 detection with the enlarged axis. Again, in my dissections (^vide fig. 29) I found that 

 there is a tiny accessory tendon of the scalenus muscle, which comes from a small 

 triangular fleshy slip alongside of the larger axial division, and is fixed immediately 

 behind it to the same vertebra. The third nerve passes between them. This diminutive 

 additional tendon, therefore, completes the normal number seven of the cervical attach- 

 ments of the scalenus, notwithstanding there being only six well-developed neck-ver- 

 tebrfe ; moreover its relation to the third nerve is, I hold, important. Inferentially this 



' Nat. Hist. Rev. 1864, p. 259. 



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