Royal Society. 393 



Iconographia Familiarum NafMralium Regni Vegetabilis delineata 

 atque adjectis Familiarum char act eribiis, ^-c. ornata. Auctore 

 "A. ScHNiZLEiN, Dr. Ph. 4to. Bonn. 



After a long interval, another numher (xi.) of this valuable series 

 of illustrations of the Natural Orders of Plants has been recently re- 

 ceived. It contains elaborate figures, with very many anatomical 

 details of the Orders noticed in it, and is quite equal in excellence to 

 the former parts of this beautiful work. As has been remarked in 

 speaking of Sturm's ' Flora,' it is to be feared that here also want of 

 support is the cause of delay in publication. Few works have been 

 slower in their publication, it being now fully fourteen years since 

 the first number appeared, and there is still much wanted to render 

 it complete. We much desire to see its continuation, as we have 

 found it of great use in our botanical studies. 



PROCEEDINGS OF LEARNED SOCIETIES. 



KOYAL, SOCIETY. 



February 12, 1857.— W. R. Grove, Esq., V.P., in the Ciiair. 



" Researches on the Reproductive Organs of the Annelids." By 

 Thomas Williams, M.D., F.L.S. 



In this paper the author seeks to establish the following general 

 proposition, viz. that there prevails throughout the Actiniadse, Echi- 

 uodermata, Rotifera and Amiclida, a special organ, which, under 

 different phases, subserves different functions, which is essentially 

 identijxahle under every modification, reducible to the same tvpe, and 

 which constitutes the root of the Reproductive system in these fami- 

 lies. To this special organ he proposes to apply the provisional 

 name of the ^'segmental organ^.'" In the chambers which are 

 enclosed by the vertical dissepiments dividing the body of Actinia, 

 convoluted tubular cords are contained which support the genera- 

 tive structures. It has not yet been proved whether the internal 

 ends of these tubides open directly into the perivisceral chamber. 

 These cords and their appended structures in the Actiniadse consti- 

 tute the type of a system of organs the prevalence of which through- 

 out the Echinodermata, Rotifera and Annelida can, he believes, be 

 clearly and satisfactorily proved. In the present memoir, however, 

 the author proposes to confine his demonstrations to the anatomical 

 varieties which the segmental organ presents in the class Annelida, 

 contenting himself with merely in a passing manner pointing out the 

 fact that the several variations of form, structure and number which 

 this organ exhibits in the several genera of this class, are represented 

 by similar variations in the different genera, especially of the class 

 Echinodermata. He hoped to show that under very ninnerous appa- 



* While he is convinced that the identity of this organ might readily be traced 

 throughout other families of the lower Invertebrata, he will not permit himself at 

 present to indulge in any wider generalization than that stated in the text. 



