355 



there is in the simple thickness of the walls a complex system of 

 water tubes. In Medusae, whose digestive cavity communicates 

 with the main cavity, water is introduced principally through the 

 mouth ; in Echinoderms, the water for digestion is introduced 

 through the mouth, but the water for the interior of the body 

 enters through the water tubes. 



Dr. Wyman exhibited an embryo, six inches long, of the 

 Greenland Whale, BalcEna mysticetus, which presented 

 some remarkable differences from the adult animal. 



Instead of the long flukes and central depression seen in the 

 adult, the tail of the embryo was rounded, as in the tail of 

 Manatus ; there was also a vertical crest above and below the 

 tail. The genital organs, in external appearance male, proved 

 to be female on the internal examination ; in the early stages of 

 the fcEtus it is impossible to distinguish them externally. The 

 thymus body was remarkably large, extending down between the 

 lungs and heart, then underneath the latter, and with its fellow 

 of the other side almost enveloping this organ. 



Dr. Wyman observed, that in a recent dissection of an Owl, 

 he had noticed, besides the metacarpal bone of the thumb, two 

 movable joints, ending with a well defined claw, forming a per- 

 fect thumb, illustrating the fact, that where there is a nail there 

 is a terminal phalanx, as in the present instance ; on the con- 

 trary, where the nail is wanting, there is generally no terminal 

 phalanx, as in the fingers of the Bat. 



Dr. Cabot said, that he had remarked at a former meeting, 

 that Bonaparte had not described the American glossy Ibis as 

 a distinct species ; he had since found that in a later Synopsis he 

 has described it as distinct, under the name of Ibis Ordi. 



Dr. W. L. Jones and Prof. John Leconte, of Athens, 

 Ga., were elected Corresponding Members of the Society ; 

 and Mr. N. D. Cotton an Immediate Member. 



