126 Mr Thomas A. Huxley on a Hermaphrodite and 



posterior segments have a similar general structure, but are 



more delicate. 



The uncini (figs. 7, 8) are very small, not more than Tt5 Vo- inch 



in length ; and it is not easy to make out their exact structure. 



Each, however, appears to be composed of a short implanted 



stem, and a blade set upon the end of this, at somewhat less 



than a right angle, like the claw of a hammer. The edges of 



this blade are minutelv denticulated. 

 %> 



Fissiparous multiplication. — It was only a minority of the 

 Protulm which presented the aspect hitherto described ; for 

 the larger number were undergoing multiplication or prolifi- 

 cation, by a process which can only be described as a com- 

 bined fission and gemmation. The prolification takes place 

 so as to separate all the segments of the parent behind the 

 sixteenth, as a new zooid ; but it is not a mere process of 

 fission, for the seventeenth segment, *. e., the first of the new 

 zooid, undergoes a very considerable enlargement, and event- 

 ually becomes divided into the nine segments of the head and 

 thorax, of the bud. These segments do not appear all at once, 

 but gradually, one behind the other. The intestinal canal of 

 the stock and of the bud are at first perfectly continuous, but 

 the peri-intestinal cavity of the bud is completely filled with 

 a mass of red granules. These would seem in some way to 

 subserve the nutrition of the young animal ; for in some free 

 zooids, apparently fully formed, all but the development of ge- 

 nitalia, the caudal segments were full of these orange gra- 

 nules, while no trace of them was to be found anteriorly.* 



It is very interesting to note the manner in which the 

 branchial plumes are developed, as it closely corresponds with 

 what Milne-Edwards describes in Terebella. Each plume ap- 

 pears at first as a quadrate palmate process of the dorsal side of 

 the first segment ; and the divisions representing the stems of 

 the future branchiae are at first mere processes, — perfectly 

 simple tubes, which do not even present annulations. 



Several modes of prolification are already known to exist 

 among the annelids. The one long since described by 0. ¥. 

 Miiller, as one of the methods of multiplication of Nais, and 



* Sars gives an account of the prolification of Filograna implexa, similar in 

 all essential points. See his Fauna littoralis, &c, pp. 88-9. 



