CLADONEMA 11ADIATUM. 65 



worth differed from Dujardiir's in having ten arms instead 

 of eight, and seven oral lobes instead of five. The number 

 of branches on the arms is variable. In some cases there 

 is only one, in others two or three are present. Probably 

 the number increases with age. The suctorial appendages 

 also vary in number. ' ' Most commonly there are three, 

 rarely only one, more frequently two, and sometimes four/' 

 They are attached to the tentacles just above the basal 

 enlargement, and, unlike the same organs in Clavatella 

 prolifera, are never used for locomotion. The zooid fre- 

 quently fixes itself firmly by means of its suckers, and the 

 arms are thrown back (" redresses ") , and stand erect 

 around the umbrella*. It swims by short and rapid 

 jerks; and when in motion, the tentacles are closely 

 retracted and the suckers outstretched. 



The lobes which surround the mouth are pedunculatcd 

 clusters of thread-cells, and arc identical in structure with 

 the capitula of the tentacles. 



The later stages in the history of the zooid have been 

 carefully observed by Mr. Holdsworth ; and his account of 

 them agrees in the main with Dujardin's. After a time 

 the umbrella begins to slough away at the top, and the 

 subumbrella is much depressed, so that the manubrium is 

 protruded through the orifice in the velum. At this stage 

 the zooid is firmly attached by its suckers, and the arms are 

 in frequent motion. 



The sloughing away continues until there is nothing 

 left but the manubrium " with the subumbrella flattened 



* " Eieri n'est gracieux comme un Cladoneme nonchalamment etale au 

 milieu cle son bassin, fuyant devant quelque danger imnginaire ou reel, on 

 solidement tapi par ses ventouses pour resister au courant, pendant qu'il 

 etale soigneusement ses longs cirrhes dans toutes les directions. On pent 

 rester des heures entieres en contemplation dovant ces organismes infimes, 

 qui semblent moins solides qu'une bulle dp savon, et qui se conservent 

 cependant en depit des vagues. des chocs et des tempetes." Vim ecdcn. 



F 



