BAMFORD— PELAGIC ACTINIARIAN LARV^ 401 



form ; no muscles can be distinguished. There are mesenterial filaments on all except 

 8 and 7 I. Convolutions are found on mesenteries 1, 2, 4, and 6, and also mesenterelles ; 

 on mesenteries 4 r and 6 I they are slight. There are no acontia. 



The ectoderm of the column has granular glands and a few spiral nematocysts ; that 

 of the stomodaeum is similar. The tissue of the mesenterial filaments has numerous 

 granular glands and a few spiral nematocysts occur in the filaments. The structureless 

 lamella is produced into long narrow processes simple or branched which bear the longi- 

 tudinal ectodermal muscles. The endoderm is a thin but compact layer on the column and 

 stomodseum ; on the mesenteries it is much vacuolated. 



Loc. Off Salomon Atoll, Chagos Archipelago, sui'face. 



7. Larva III. Ovactis indiana, n. sp. (PL 24, fig. 15.) 



The larva is like the last, but it is shrunken in places; its length is 2 '5 mm. and its 

 maximum diameter 275 mm. The peristome is mtroflected and there is no buccal cone; 

 the edge of the peristome is seen in the sections to be produced into protuberances, the 

 beginnings of tentacles, above some of the mesenterial chambers. 



The stomodseum has a broadly elliptical cavity ; it possesses no ridges and the 

 epithelium of the sulcar groove is not difierentiated ; a hyposulcus and hemisulcl 

 are present. 



The ectoderm of the stomodseum is in direct continuity with the mesenterial 

 filaments. There are 17 mesenteries near the oral end, 8 on one side and 7 on the 

 other side of the two directives. Mesentery 8 is the shortest, then mesentery 7 I, and 

 these do not extend below the stomodreum ; the next shortest is mesentery 7 r. Near 

 the oral end there are 17 inter-mesenterial chambers, but below the stomodseum only 

 14. Mesentery 8 and mesentery 7 / have no mesenterial filaments; the rest have 

 filaments, except mesentery 7 r, which has a terminal swelling not continuous with the 

 ectoderm of the stomodseum but provided with spiral nematocysts. The filaments of the 

 even numbered mesenteries and also 1 r and I are convoluted. In section the mesentei'ies 

 are leaf-like and those which have convolutions have also mesenterelles. Acontia are 

 absent. 



In the ectoderm of the colunm are numerous glands, some large, stained blue, con- 

 taining large granules, others small, stained red, containing small granules. Nematocysts 

 of the common form, long and narrow with a close spiral, are numerous, and at the oral 

 end and on the peristome are a few exceptionally large nematocysts, deeply stained, with 

 straight axes. On each of the tentacular prominences, or on the cohnun just below each, 

 is a group of mucous gland cells. Greenish spherical bodies, which in some cases have 

 a rough external surface, are fairly numerous near the base of the ectoderm ; in transverse 

 section they show two or three lightly coloured spots. The mesenterial filaments have 

 closely packed granular glands and a few spiral nematocysts ; the stomodaeal ectoderm 

 is similar, with additional long, narrow and deeply stained nematocysts. The ectodermal 

 muscles are carried on rounded projections of the structureless lamella. There is as yet no 

 trace of muscles, but banners have commenced to form, 



Loc. Lat. 4° 16' S., long. 71° 53' E., North of Chagos Archipelago, 25 fathoms. 



51—2 



