728 Leuckart: Bericht üb. d. wissenschaftlichen Leistungen 



which are the mouths of the larger dactylopores. Dactylopores of 

 the smaller kind also present; their mouths appear as minute oval 

 apertures over the bases and sides of the spines. Styles absent in 

 the dactylopores. Gastropores deeply seated in hollows between the 

 bases of the spines; wiih deeply placed styles. Ampullae absent in 

 the unique specimen. Dactyloaooids oftwo kinds, the larger attached 

 by elongated bases within the spout-like cavities of the larger dactylo- 

 pores, incapable of retraction within the pores; the smaller minute ; 

 entirely retracted when at rest. Gastrozooids cylindrical, with six 

 tentacles and four basal canals. Gonophores unkown. Sp. ecliinata 

 n. sp. Rio de la Plata. 



AUopora Ehrbg. Corallum branching, but frequently not so 

 as to form a flabellum. Pores in regulär cyclo-systems only, excep- 

 ting in A. nobilis Kent, where some of the Systems are not perfected. 

 Tendency to alternate gemmation present, but weak and usually 

 obscured by an abundant growth of coenenchym. Cyclo-systems al- 

 ways scattered over the faces of the branches as well as situated at 

 their lateral margins; often entirely sporadic in disposition. Dactylo- 

 pores with a more or less rudiraeutary style affixed to those parts 

 of their walls which are outermost in the Systems. Gastropores 

 simple tubulär, with a brush-like style. Ampullae sometimes pro- 

 minent, sometimes scarcely showing at the surface, Dactylozooids 

 attached by elongated bases to the sides of their pores occupied by 

 the styles ; partly retracted within the pores, partly beut 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 containig two or three ovoid gonophores with club: 

 shaped spadices. Structure of gonophores of female Stocks unknown. 

 St. profunda n. sp. Rio de la Plata. 



Stylaster Gray. Corallum arboresceut usually Üabelliform. 

 Pores in regulär cyclo-systems only. A strong tendency to the deve- 

 lopment of these cyclo-systems on the lateral margins of the bran- 

 ches only. Cyclo-systems arising from one another by alternate 

 gemmation. Dactylopores and zooids as in Allopora. Ampullae 

 usually prominent on both faces of the flabellum. Gastrozooids cylin- 

 drical, with numerous basal canals and eight tentacles. Gonophores 

 of male Stocks as in Allopora. Structure of female unkown. St. 

 densicauUs n. sp. Rio de la Plata. 



Astylus n. gen. Corallum forming a small and delicate fla- 

 bellum. Pores in regulär 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. 

 Gastropores divided into two Chambers, an upper and an lower, by 

 a constriction of their walls. Opening between the Chambers reu- 



