REPORT ON CORALS — HYDROCORALLIISLE. 97 



affixed to those parts of their walls which are outermost in the systems. Gastro- 

 pores, simple tubular, with a brush-like style. Ampullae sometimes prominent, some- 

 times scarcely showing at the surface. Dactylozooids attached by elongate bases to the 

 sides of their pores occupied by the styles ; partly retracted within the pores, partly 

 bent upwards when at rest within the wide pore mouths. Gastrozooids dome-like in 

 shape, with twelve tentacles and numerous basal canals. Gonangia in male stocks 

 containing two or three ovoid gonophores with club-shaped spadices. Structure of 

 gonophores of female stocks unknown. 



8. Stylaster, Gray. 



Coenosteum arborescent, usually flabelliform. Pores in regular cyclo-systems only. 

 A strong tendency to the development of these cyclo-systems on the lateral margins 

 of the branches only. Cyclo-systems arising from one another by alternate gemmation. 

 Dactylopores and zooids as in Allopora. Ampullar usually prominent on both faces 

 of the flabellum. Gastrozooids cylindrical, with numerous basal canals and eight 

 tentacles. Gonophores of male stocks as in Allopora. Female stocks with prominent 

 rounded ampullae {Stylaster roseus). 



9. Stenohelia, Saville Kent (Ann. and Mag. Nat. Hist., 1870, vol. v. p. 120). 

 Coenosteum delicate, branching, flabelliform ; pores in regular cyclo-systems only. 



Cyclo-systems all turned towards one face of the flabellum. Dactylopores without 

 a style or with a very rudimentary one. Gastropores very deep and curved, so as to 

 tubulate in all but the older branches the entire lengths of the axes of the branches, 

 with small styles seated at the bottoms of these tubes and directed parallel to the axes 

 of the branches at right angles to those of the mouths of the cyclo-systems. 



10. Conopora, Moseley. 1 



Coenosteum delicate ; with pores in regular cyclo-systems ; branching irregularly, the 

 cyclo-systems having their mouths turned in all directions. Cyclo-system masses conical 

 in form. Both kinds of pores devoid of a style. Gastropore with two chambers, the 

 upper opening into the lower by a circular aperture. Differs from Cryptohelia and 

 Astylus in having no lid or tongue-like process and in not forming a regular flabellum. 



11. Astylus, Moseley. 2 



Coenosteum forming a small and delicate flabellum. Pores in regular cyclo- 

 systems, all placed on one face of the flabellum. Cyclo-systems forming cylindrical 

 masses prominent from the branches, and with their axes directed at right 

 angles to the plane of the flabellum. Style absent in both kinds of pores. Gastro- 



1 Prelim. Report, Phil. Trans. Roy. Soc, 1878, part 2., p. 503. 2 Ibid, \\ 477. 



(ZOOL. CHALL. ESP. — PART VII. 1880.) G 13 



