Key to the genera of the ISID.E. 



(Generic names enclosed in brackets indicate that such genera are not represented in the Siboga collection). 



Isidinse : 



Spicules densely tuberculate spindles, calyces included Isis 



Ceratoisidinae: 



Calyces not uniserial, and with a crown of points formed by large, needle- 

 like spicules. 



Colony simple ; or, if branched, with branches springing from the calcareous 

 internodes. 

 Calyx with an external layer of flattened, bar-like spicules with 



rounded ends (Lepidisis) 



Calyx with spindles or needles only Ceratoisis 



Colony branched, branches arising from horny nodes Acanella 



Calyces sometimes uniserial, without a crown of points. 



Colony unbranched ; calyces uniserial (Bathygorgia) 



Colony branched, branches from calcareous internodes. 



Coenenchyma with spicules (Callisis) 



Coenenchyma without spicules (Sclerisis) 



Branches from horny nodes (Isidella). 



Mo psei nse : 



Calcareous internodes with serrated ridges (Acanthoisis) 



Calcareous internodes without serrated ridges. 



Calyces uniserial, with true opercula Peltastisis 



Calyces not uniserial, no true opercula. 



Spicules of calyx ctenate scales, or with thorny points .... Mopsea 

 Spicules of calyx spindles, with true verrucae (Chelidonisis) l 



Synoptic view 9f the genera and species of ISID.E secured by the Siboga. 



* The asterisk (*) denotes a new species. 



Is idinae. 

 Isis. 



/. kippuris, L *reticulata. 



M o p s e i n ae. 



Mopsea. 

 M. *flava, M. *alba. 



Peltastisis. 

 P. *uniserialis, P. *cornuta. 



Ceratoisidinas. 

 Ceratoisis. 



C.paucispinosa, C. philippinensis, C.*wrighti, 

 C. s.'r 



Acanella. 



A. *sibog&, A. *weberi, A. sp.1 



1 This form shows affinities with the fsidin<z in the form of its spicules, which are much like those of Isis hippuris; but has 

 a rather thin crenenchyma and evident calyces, characters which allie it with the Mopseina. See STUDER, Alcyonaires provenant des 

 Campagnes de 1'Hirondelle, 1901. p. 39 and Plate Iv, fig. 9. 



