BAMFORD— PELAGIC ACTINIARIAN LARV^ 399 



but their relationship is less clear (figs. 8 — 11). The whole would appear to be a stage In 

 the growth downwards of the stomodaeal ectoderm to form the mesenterial filaments. No 

 trace of such structures are found in connection with the incomplete mesenteries. 



The ectoderm resembles that of the last larva (III.) with both types of nematocysts; 

 mucous cells are conspicuous. The stomodaeal ectoderm and the mesenteries are likewise 

 similar. The muscle banners are especially conspicuous. The endoderm is also similar, 

 ovoidal nematocysts being particularly abundant on the mesenteries near the stomodfeum. 

 It exhibits a quantity of granular, greenish-yellow substance and patches of large bright 

 yellow granules. 



Loc. To the South of Saya de Malha Bank, surface. 



Cerianthidea. 



Three larvse belong to this division ; one is a new species of Dactylactis, v. Beneden *, 

 and the others approximate most closely to Ovactis, v. Beneden t, but are new. All, as is 

 usual in the division, show the right side preceding the left in development, and larvae II. 

 and III. are in a stage when there is only present the right mesentery of the couple in 

 formation. The orientation is the same as that given by v. Beneden ; the terms right (r) 

 and left (l) are used for the sides to the right and left of the dii'ectives when viewed from 

 the position of the chamber of multiplication. 



5. Larva I. Dactylactis cerfensis, n. sp. (PL 24, fig. 13.) 



The larva is translucent and measures 3 mm. from the aboral end to the end of the 

 longest tentacle by 2 mm. in greatest diameter. The peristome is introflected and without 

 lips ; no aboral pore is present. Eleven marginal and ten labial tentacles are developed ; 

 the former approximate to each other at the base and there is no circular groove separating 

 them from the column. There are 12 mesenteries, 5 on each side of the 2 directives, and 

 12 chambers, 1 of direction, 1 of multiplication and 5 on each side. A marginal tentacle 

 is found above each chamber except that of multiplication ; the labial tentacles lie against 

 the marginals, but there is no tentacle above chamber 5 /. 



Towards the oral end mesenteries 5 r and 5 I do not reach the stomodseum, but in 

 lower sections both reach it, though 5 I only through 2 sections ; both of these mesenteries 

 stop short considerably above the aboral end ; 5 I has no filament, but owing to the loss of 

 certain sections no statement can be made as to 5 r. The directives are the shortest of 

 the remaining mesenteries and have no filaments. The latter are found on all the rest and 

 are markedly convoluted on 1, 2 and 4. No acontia are present. There is a deep sulcus 

 with flagellated cells diff'erentiated for a considerable distance, but the presence of a 

 hyposulcus and hemisulci is doubtful. 



The marginal tentacles are quadrilateral in section though slightly flattened. The 

 ectodermic muscles are most highly developed on their adaxial sides, but near the column 

 they are well developed on their abaxial sides also. Their nematocysts are long and 

 narrow with a close spiral filament. There is no glandular zone and the ectoderm of the 

 column is without glands. The latter has a few tentacular nematocysts with others larger 



* Plankton Expedition, Les Anthozoaires, 1898, p. 103. t loc. cit., p. 84. 



SECOND SERIES- ZOOLOGY, VOL. XV. 51 



