Royal Society. 51 



for retaining or expelling their contents, communicate by large ori- 

 fices with the nasal canals, and appear to correspond in situation 

 with the antra, frontal sinuses and ethmoid cells. The author gives 

 a minute anatomical description of these muscles, and an account of 

 their modes of action ; the adjustments of the apparatus being such 

 that the outer passage may be closed or opened above or below the 

 anterior pouches. When the outer passage is closed, the posterior 

 pouches can be distended and the anterior emptied ; while the con- 

 verse may be effected when the passage is open. The use of the 

 pouches appears to be to buoy up the head, so that on the porpoise 

 rising from deep water, the opening for breathing comes first to the 

 surface and admits of the animal's sleeping in that position, while its 

 whole body remains immersed in the water. 



" On Motion in the Lumbar Division of the Spine in Birds." By 

 George Oakley Fleming, M.D., F.L.S. Communicated by Thomas 

 Bell, Esq., F.R.S. 



The author gives quotations from the works of Cuvier, Blumen- 

 bach, Tiedemann, Macartney, Vicq d'Azyr, Carus, Earle, and Roget, 

 in proof of its being the prevalent opinion among comparative phy- 

 siologists that the dorsal and lumbar portions of the spine form alto- 

 gether a rigid structure, not admitting of the least perceptible flexion. 

 But from his observations of the form of the articulating surfaces of 

 the lumbar vertebrae, which appear to be adapted to lateral motion, 

 the author was led to conclude that, although flexion in the mesial 

 plane is effectually prevented, some degree of lateral flexion actually 

 takes place. The number of articulations in this part of the spine, 

 he observes, varies in different birds : thus in the sea-gull, there are 

 several articulations in the dorsal and lumbar portions ; while, in the 

 peacock, there is only one moveable vertebra; the remaining dorsal 

 being united together, and all the lumbar vertebrae being consoli- 

 dated and anchylosed with the sacrum ; thus forming two firm and 

 immoveable pieces between which the moveable vertebra is placed. 

 The flexion of the spine forwards is prevented by the great breadth 

 of the spinous processes and their projections at right angles to the 

 bodies of the vertebrae ; and frequently also by the addition of a 

 number of thin, fiat long bones which are applied by their flat sur- 

 faces on each side of the spinous processes ; and also by strong flat 

 ligaments, situated between each spinous process, like the ligamen- 

 tum nuchae of herbivorous quadrupeds. For the purpose of guard- 

 ing against pressure on the spinal cord during the lateral flexion of 

 this part of the spine, the spinal canal is enlarged laterally at the 

 centres of motion. The paper is illustrated by drawings of the parts 

 described. 



March 19. — " Investigation of the Power consumed in overcoming 

 the Inertia of Railway Trains, and of the Resistance of the Air to 

 the motion of Railway Trains at high velocities." By P. W. Barlow, 

 Esq., F.K.S., M.I.C.E. 



The object of the author in this inquiry is to obtain a more cor- 

 rect knowledge than has hitherto been possessed of the resistances 

 which the air opposes to the motion of locomotive engines at great 



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