3i 



however, that the relative widths of the brachycnemes and the level at which they lost their 

 ciliated lobes of their filaments seemed to show that the longer one was the second in each 

 quartette; the relative lengths of the macrocnemes could not be determined. If this be the actual 

 sequence of the brachycnemes it constitutes a third type of arrangement of the deuterocnemes, 

 differino- from the two mentioned above (p. 15), but I do not feel sufficiënt confidence in the 

 reliability of my data to describe it definitely as a type. 



So far as could be ascertained the mesenterial filaments had the usual cerianthan 

 arrangement and structure, but my preparations did not show any craspedonemes, although I 

 cannot state positively that they were absent. The fertile mesenteries contained both ova and 

 spermatozoa, the species being therefore hermaphrodite. 



Larval Forms. 

 Genus Apiactis van Ben. 

 Synonym: Apiactis van Beneden, 1898. 



Cerianthidae whose larval forms are more or less conical is shape, with no constriction 

 of the column wall immediately below the bases of the tentacles. Marginal tentacles short, 

 digitiforni; the median tentacle developes early, and the remaining ones quickly succeed the 

 corresponding mesenteries. The oral tentacles are small, tuberculiform. Siphonoglyph and directive 

 mesenteries short. Acontia in some cases slow in development. 



I have modified van Beneden's definition of the genus so that it will include the form 

 to be described below, which seems most naturally referable to Apiactis, although it differs 

 from the type species in numerous details. 



4. Apiactis oèconica n. sp. 



Stat. [36. Ternate anchorage. Plankton. 1 ex. 



Stat. 165. Anchorage on North-east side of Daram Island, (False Pisangs), east coast of Misool. 



Plankton. 1 ex. 

 Stat. 172. Anchorage between Gisser Island and Ceram-Laut. Plankton. 3 ex. 

 Stat. [84. Anchorage oft" Kampong Kelang, south coast of Manipa Island. Plankton. 1 ex. 



General form. — The column is conical in form, the aboral pole being truncated as 

 shown in PI. I, fig. 4 and 5, two of the examples from Stat. 172, however, being rounded at 

 the aboral pole and much less tapering. The summit of the column is surrounded by a circle 

 of marginal tentacles varying in number from 16 to 19, short and digitiform in shape and the 

 one corresponding to the directive mesenteries somewhat smaller than the rest (fig. 4). The oral 

 tentacles are small and tuberculiform and, indeed, could not be distinguished clearly in all the 

 specimens, nor could they be readily identified in sections. In one example, in which they were 

 especially distinct, they were nine in number, four on one side of the median line and five on 

 the other, the most medial on each side corresponding to the second intermesenterial chamber 

 on each side of the directive chamber, the three median chambers being without corresponding 

 oral tentacles. 



31 



