16 G. HERBERT FOWLER. 



Foraminifer, or some similar body (v. Moseley, ' Rep. Chall. 

 Zool./ ii, Madrep., pi. xv, figs. 1, 2) ; but the adult is entirely 

 free, and therefore more or less at the mercy of natural acci- 

 dents, such as currents. Correspondingly with this condition, 

 but unlike that of the attached forms (Lophohelia, Caryo- 

 phyllia, &c.) it developes no " Rand-platte," (vide p. 8), but 

 the polyp can be wholly retracted within the calyx (cf. (2) 

 fig. 2). The absence of the "Rand-platte" implies almost neces- 

 sarily the absence of extracalicular calicoblasts ; the calyx 

 must therefore be deposited by those internal to the corallum. 

 As a consequence of these facts, the calyx of Flabellum, if it 

 be not an epitheca, would be homologous with that part of 

 the theca of Lophohelia, &c, which lies internal to the dark 

 line of growth mentioned above (p. 7) ; and a comparison of 

 fig. 16 with figs. 4, 5, will show that there is no discordance 

 between the two structures. 



In both forms, as is generally the case, the regions due to 

 separate centres of coral secretion are bounded by sutures ; 

 and of these regions those marked T. (thecal), and S. (septal), 

 in all three figures certainly appear to be respectively homo- 

 logous. Even the way in which the dark line in Lophohelia 

 curves inwards to the ectoccelic septum (owing to the fact that 

 at the lip the latter does not project so far peripherally as an 

 entocoelic septum) agrees with the involution of the septa in 

 Flabellum. The fact that in fig. 5 the centre of calcification 

 of the entocoelic septum projects outwards through the line of 

 growth, is of course attributable to the pseudo-costse occurring 

 at the lip of the calicle of this species of Lophohelia which are 

 produced by extra-calicular calicoblasts and are not therefore 

 represented in Flabellum. 



In fig. 17 is drawn a transverse section through a part of the 

 pedicle, that is to say a section through the corallum of an 

 embryo Flabellum measuring about 2*25 mm. in diameter and 

 possessing six primary and six secondary septa. The relations 

 indicated by the sutures are the same as in the former section. 

 The successive laminae showing the conversion of the embryonic 

 calyx into a nearly solid pedicle are well marked. 



