— u - 



On comparing these specimen s with the description and figure of 

 Duchassaing and Michelotti, it was found that while there was agree- 

 ment in the number of tentacles, for from the number of mesenteries 

 it may be assumed that there were thirty-seven tentacles in the polyp 

 examined, there is a remarkable dill'ereuce in size, since the description 

 g-ives the height to be 4 cm. while the figure, stated to be of naturai 

 size, shows it to be considerably over 3 cm. with a diameter in the 

 distai portion of 1.5 cm. Either the size is a comparatively unim- 

 portant factor in the distinction of species of Zoanthus or there has 

 been a mistake in the labelling of the Turin specimens. The former 

 view seems the more probable. 



As regards the value of the number of mesenteries as a basis for 

 the classification of the Zoanthids, it may be said that from their 

 mode of growth- it might readily be supposed that their number was 

 inconstant, increasing with age. And this is no doubt true to a certain 

 extent so far as egg-individuals are concerned. In polyps of Z. sociatus 

 taken in different localities I have found, however, that the number 

 of mesenteries is fairly Constant, five individuals for instance pos- 

 sessing respectively 46, 50, 52, 60 and 60 mesenteries ; Duerden has 

 found in seven polyps of one colony of bis Z. flósmarinus from 50 to 

 60 tentacles and in tour individuals from another colony 48 to 56; 

 and Erdmann (1885) in 13 individuals of Z. danae Hert. found from 16 

 to 50 mesenteries. The mesenteries are continued with very slight 

 diminution in numbèrs into the stolons, but since the buds arise from 

 the surface of a stolon it might be expected that they would at first 

 possess a mudi smaller number of mesenteries than the adult polyps, 

 perhaps about hall as many. The difference must, however, be quickly 

 remedied, since in a bud of Z. sociatus measuring only 2 mm. in height 

 I find 47 mesenteries, while in another 3.5 mm. long, the number is 36. 



It would seem, then, that there is a tendency for ali the potyps of 

 a species to acquire a somewhat definite number of mesenteries and 

 tentacles, and if this be assumed as a basis for classification, Duchas- 

 saing and Michelotti 's Z. flósmarinus must be regarded as a good 

 species, notwithstanding its marked similarity in other particulars to 

 my Z. sociatus and the Z. flósmarinus of Duerden and myself. The 

 last-named fbrm is to be regarded as different from the present species, 

 and I may say that I ani convincevi that it is identical with the forni 

 I described (1880) as Z. sociatus. Duerden too (1002) identifies his 

 flósmarinus with my sociatus and with these two corrections we would 

 have a clean slate were it not that Verrill (1000) has introduced some 

 discrepant identifications. He recognizes the distinctness of Duchas- 

 saing and Michelotti 's flósmarinus and identifies correctly Duerden 's 

 flósmarinus with my sociatus, but my flósmarinus he makes identical 



