178 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tion includes 187 species (61 belonging to Dendronephthya) ; 108 are 

 new, but 53 of these belong to Dendronepldhya. Two new genera are 

 established, Dactylon&phthya appended to the NephthyidaB, and Para- 

 belemnon among the Veretillids. There is also a full description of 

 Studeriotes mirabilis n.n. ( = Studeria mirabilis Thomson), and Cacto- 

 gorgia Simpson, two new and remarkable types previously reported. 

 Perhaps the most interesting result of this memoir is the evidence that 

 the genera Studeriotes, Dactylonephthya, and Cactogorgia are annectent 

 types related to Alcyonids, Nephthyids, and Siphonogorgids. 



Porifera. 



New Family of Calcareous Sponges.* — R. W. Harold Row reports 

 on Crossland's collection of Calcarea from the Sudanese Red Sea, 

 which includes sixteen species, six new. The collection is extremely in- 

 teresting, owing to its strikingly intermediate character between the 

 faunas of the Mediterranean and Atlantic on the one hand, and of the 

 Indian Ocean on the other. Of much interest is the author's account 

 of a new type, Grantilla, which requires a new family, Grantillidas. A 

 dermal cortex is always present covering over the chamber layer. The 

 skeleton includes sub-dermal "prochiacts" (modified triradiate spicules), 

 and may or may not include sub-dermal sagittal triradiates and quadri- 

 radiates. Subgastral prochiacts may or may not be present. Chambers 

 and skeleton arrangement are as in the Grantidse. 



Another new genus, Kebira, is of unusual interest as a living member 

 of the Pharetronidre, an almost wholly fossil family, and in having 

 peculiar triradiates, the paired rays of which are vestigial. The de- 

 veloped fibres, which look like oxeas, lie radially disposed, or inclined but 

 little to the radial direction, in the chamber-layer. The canal system is 

 leuconoid, with large sub-dermal cavities, inhalant and exhalant canals. 



Hexactine Spicules.! — R. Kirkpatrick gives reasons for the following 

 conclusions. The regular hexactine spicule (with three axes crossing at 

 right angles through a common centre and corresponding with the axes 

 of the regular crystalline system) was primarily formed in Hexactinellid 

 sponges, as being the most economical and efficient means for supporting 

 the strands of a syncytial network ; for, in the gastrosome at any rate, 

 the microscleres would be useless for upholding the body or flagellated 

 chambers, but most efficient for the vitally important function of keeping 

 open the meshes of the dermal network. The geometrical forms of cubes, 

 squares, or lines (hexactins, stauractins, amphidiscs), arise in correspon- 

 dence with the requirements for supporting cubical spaces, surfaces, or 

 concentric lamiiue. The support of flagellated chambers and of the 

 body as a whole was a later need, and was effected by the development 

 of microscleres into parenchymal and auxiliary surface macroscleres. 

 The identity of axes of the regular hexactin with those of the regular 

 crystalline system is a coincidence, the real determining factor of the 

 shape being a biological one. 



* Joum. Linn. Soc. (Zool.) xxxi. (1909) pp. 182-214 (2 pis. and 8 figs.). 

 t Ann. Nat. Hist., iv. (1909) pp. 505-9. 



