42 



DE. J. MUEIE ON THE MANATEE. 



the sixth, then- origin can be traced towards the medulla oblongata outside the latter. 

 As reo-ards the compound eighth nerve, funiculi respectively constituting glosso-pha- 

 rangeal, pneumogastric, and spinal accessory are clearly distinguishable. The ninth 

 nerve (hypoglossal) is equally manifest, and derives its filaments from a more median 

 line than the divisions of the eighth. In short, the cranial nerves, as a whole, are 

 derived from nearly their normal situation, as obtains in the Mammalia generally. 



Lastly, in connexion with the brain, I have in Plate IX. given the vascular distribu- 

 tion. The circle of Willis is complete; but the internal carotid and basilar artery 

 seem relatively small, M'hile the other cerebral branches take on somewhat a retial 

 character. 



Concluding HemarTcs. — The present communication of necessity has led to a few items 

 of controversy ; but while supporting my own former observations and views, I have no 

 wish to detract from the really useful papers of my fellow anatomists. 



The most important points are those in connexion with the brain and the cranial 

 and cervical nerves. As to the brain, I with pleasure acquiesce in the emendation of 

 its comparatively smooth surface ' ; but I am dubious as to Garrod's figures giving its 

 natural contour and details correctly, sine qua non. I moreover think the minor dif- 

 ferences of special parts mean nothing more than variety in expression rather than 

 established facts ; for with separate specimens to work on, and under dissimilar condi- 

 tions and aspects, each individual has consequently seen from his own point of view. 

 As to the cranial nerves, I could have much wished Dr. Chapman had supplemented his 

 remarks by a good figure of the brain's base ; for in his attributing my lettered eighth 

 nervous funiculi {I. c. pi. xxv. figs. 32, 33) to a pars intermedia considerable ambiguity 

 arises ; besides, against his idea there is the weighty fact that the said filaments spring 

 as usual from the side of the medulla oblongata. 



' The accompanying woodcut (fig. 2) is reduced from a rough sketch made now fully ten years ago, pre- 

 vious to extraction of the brain of the female Manatee dis- 

 sected by me. By accident it and a few notes had got mislaid 

 and lost sight of when preparing my material for the press. 

 Had it been otherwise they might have saved me falling into 

 errors of interpretation of supposed convolutions, magnified by 

 spirit-preparation and surface-scaling. I do not offer this as 

 an apology ; for one must be judged by their publication, be 

 it right or wrong. To me, however, Prof, liolleston's words 

 have some meaning : — " Persons, however, to whom an inner 

 conviction of their own accuracy may be dear in the face of 

 adverse criticism, may learn from this the advisability of pre- 

 serving such documentary evidence as that to which I have 

 referred." (Eolleston versus Laukester, " Blood-corpuscles of 

 the Annelides," Cambr. Journ. of Anat. and Physiol, vol. sii. 

 p. 401, April 1878.) 



