35 



March 19, 1851. 



Dr. C. T. Jackson, Vice-President, in the Chair. 



Prof. Wynian made some statements with regard to the 

 structure of the spinal cord in Bats. 



Cuvier has stated as a general law, that the size of the bulging 

 portions of the spinal cord is in proportion to the " force " of the 

 limbs opposite to them. This is not strictly true, for in birds 

 the posterior enlargement is the largest, while the wings are 

 more muscular and stronger than the legs, except in a few 

 instances ; the enlargements of the chord are not therefore pro- 

 portional to muscular force ; if the legs and wings are compared 

 with reference to their sensibility, this will be found to be the 

 greatest in the former ; the wings in consequence of being com- 

 pletely invested with feathers are not adapted to receive sensitive 

 impressions. In bats the anterior enlargement far surpasses ia 

 size the posterior and extends through the larger portion of the 

 cervical region and to a short distance into the dorsal. Cuvier 

 and Spallanzani proved that these animals are able to fly through 

 intricate passages in the dark without touching the walls, and 

 this independently of the senses of sight and hearing ; a faculty- 

 thought to be due to the sense of touch alone, the organ of which 

 is a minute network of nerves, arising from the superior enlarge- 

 ment of the spinal cord and distributed throughout the wing. 

 Thus it would seem that these portions of the cord are intended 

 to be in relation to the function of sensation rather than that of 

 motion. 



Mr. Ayres presented a description of the species of Holo- 

 thuria, which has been supposed to be identical with Hoi. 

 squamata, and which is noticed under that name in Dr. 

 Gould's Report on the Invertebrata of Massachusetts. 



It is undoubtedly the squamata of Fabricius, in the Fauna 

 Grognlandica, but it has been shown by Duben and Keren to be 

 distinct from the original squamata^ and as it belongs to the 

 genus Cuvieria, it is called by them Cuv. Fabricii. It is dis- 

 tinguished from the original type by having the skin of the ven- 



