135 



prove to be nothing but nurses of polyps ; an idea which has 

 since been repeated by others, but without any proof. Van 

 Beneden, on the contrary, who has made the most extensive inves- 

 tigations in the development of these animals, asserts positively 

 that there is no identity between these embryos of polyps and 

 true Medusa ; that the resemblance is merely apparent and exter- 

 nal, and that the bud, after being freed, fixes itself and becomes 

 a new polyp. He has even drawn a hypothetical figure which is 

 intended to show the manner in which this supposed transforma- 

 tion takes place in Tubularia. (See Mem. de I'Acad. de Brux- 

 elles, Tom. 17.) 



Mr. Desor's investigations show that the embryo of Syncoryne 

 is neither a nurse nor a female polyp, but that it became really 

 a genuine Medusa, (the Oceania fAibulosa), which does not turn 

 into a polyp, but which is found afterwards to have its ovary 

 filled with eggs, which are laid, and probably produce in their 

 turn young Syncoryne. 



The two animals Syncoryne and Oceania fuhulosa, widely dif- 

 ferent as they are in shape and structure, being thus proved to be 

 the same animal, like the caterpillar and butterfly, they ought 

 henceforth to be designated under one name. The rule in such 

 cases generally is to retain the name of the perfect form. But 

 as the Oceania in question does not agree exactly with the figure 

 given by Ehrenberg, Mr. Desor proposes to adopt in this case 

 the name of Syncoryne* 



Mr. D. laid before the Society a series of drawings illustrating 

 the above development. 



Mr. Adams exhibited to the Society a daguerreotype view 

 of a spider's claw as seen through a microscope. It was a 

 very perfect representation of the object, and according to 

 Mr. Adams, the first successful application of this process 

 in this country to such a purpose. 



Donations of books were announced, from Dr. R. W. 

 Gibbes of Columbia, S. C, Hon. R. C. Winthrop, and from 

 Mr. Isaac Lea of Philadelphia, for which see Quarterly 

 List. 



* See note page 139. 



