342 



Prof. H. J. Clark presented a communication, in which he 

 stated that he had recently discovered the eggs of Tubula- 

 ria ; and that it was owing to their minute size and exces- 

 sive transparency that they had not been seen before. In 

 this connection, he described the mode of formation of the 

 meduso-genital of these Ilydroids, showing that it differs from 

 all that has been published hitherto.* He also announced 

 his discovery of the female of Mhizogeton fusiformis, Ag. 



The ovigerous meduso-genital is borne singly upon a stem, which 

 is at least two-thirds as long as that of the sterile form. The young 

 leave their parent in the planula state by breaking through the wall 

 of the medusoid : but the latter being covered by a filmy, chitinous 

 investment, the planules are held in it for a while, and sometimes until 

 all of them have escaped from the parent ; and then, being grouped 

 in a close mass about the latter, they very naturally would be, at first 

 sight, mistaken for medusoids attached to a hydroid head, in the same 

 Avay as occurs in Clava. This is rendered all the more deceptive from 

 the fact, that when the medusoid is em2:)ty it elongates, and the wall of 

 the proboscis presses more or less closely against the wall of the bell, 

 and the two together seem as if they were the two walls of a hydroid 

 head. This peculiarity has led Prof Agassiz to state in the fourth 

 volume of his " Contributions," in regard to the male medusoid, that 

 " one and the same individual medusa, after discharging its reproductive 

 organs, is meiamorjyhosed into a hydra." This, Prof. Clark believed, 

 was not true ; nor was there any thing in the description or illustrations 

 in the" Contributions" which warranted such a statement. The proper 

 explanation is, that the medusoid withers and becomes resorbed ; and 

 then a hydroid head develops, in all probability, directly from the end 

 of the old stem. 



Mr. A. E. Verrill read the following papers : — 



Description of a Species of Samia, supposed to be new, 

 FROM Norway, Me. — By S. I. Smith. 



Among the Attaci collected by me the past season, there is a pair of 

 moths closely allied to Samia Cecropia Hiibner, which I am unable to 

 refer to any described species. A single specimen of the same species, 

 obtained in 1862, was forwarded to the Museum of Comparative Zool- 

 ogy at Cambridge, and there' pronounced new by Mr. A. S. Packard, 

 jim. I have therefore, with the entire approbation of Mr. Packard, 



* This is publislied, witli full details, in the " American Journal of Science" for 

 January, IS&i. 



