376 



organ," in the feature of their having two limbs, being therefore 

 looped, although only rudimentarily. The author then proceeds to 

 give an account of his studies into the history of this organ amongst 

 the grotesque and highly varied species of the genus Polynoe. They 

 have rendered it certain that throughout the family of the Aphro- 

 ditaceae there obtains but one type of segmental organ, and that 

 upon it always are ingrafted the generative structures. 



At this stage the attempt is made to show that the segmental 

 organs of the Echinidae, Asteriadae and Holothuriadae conform, 

 structurally and functionally, in the most remarkably intimate man- 

 ner with the typical standard exhibited by this organ in the Aphro- 

 ditaceae. But between these Echinoderm and Annelidan families the 

 author attempts to indicate other zoological affinities. He shows, 

 that, according to his researches amongst the Aphroditacese, there is 

 no trace whatever to be discovered of a blood-vascular system. In 

 this respect they correspond with the Echinidan and Asteridan fami- 

 lies. He shows that in the Aphroditacese the general cavity is never, 

 under any circumstances, used as an incubatory chamber. In this 

 point of their generative history the Echinidae and Asteriadae exactly 

 agree with the Aphroditacese. 



The author regrets, that, in consequence of the difficulty of obtain- 

 ing specimens, he is obliged to defer to a second memoir many special 

 points of anatomical structure and physiological relations, the deter- 

 mination of which he still feels to be necessary to the complete 

 history of the segmental organ in the Annulose and Radiated classes. 



The paper is illustrated by numerous drawings. 



III. "Addition to a Memoir on the Determination of Un- 

 known Functions that are evolved under Definite Inte- 

 grals." By J. GOMES DE SOUZA, Esq. Communicated by 

 Dr. SHARPEY, Sec. U.S. Received November 1, 1856. 



In his previous communication (Proceedings, June 12, 1856) the 

 author developed <px in terms of the function A e m t*. In the present 

 communication he developes in a more general way, using terms of the 



form A r J*e n Hr(e0}M r )dh;, the function of OT being assumed at plea- 



