5 

 Key to the genera of the Isid.e. 



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



I sidi nse : 



Spicules densely tuberculate spindles, calyces included Isis 



Ceratoisidinje: 



Calyces not uniserial, and with a crown of points formed by lar^e, needle- 

 like spicules. 

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

 internodes. 

 Caly.x 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). 



M o p s e i n se : 



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) ^ 



Synoptic view of the genera and species of Isid.e secured by the Siboga. 



•■ The asterisk (*) denotes a new species. 



Acanella. 



I s i cl i n ae. 

 Isis. 



/. hippiiris, I. '^7'cticiilata. 



Ceratoisidina;. 



Ceratoisis. 



C. paucispinosa, C. philippinensis^ C. *xvrighti, 

 C. sp.} 



A. *sidog(p, A. ^ivebcri, A. sp.t 

 M o p s c i 11 ;t. 



Mopsea. 



M. *ßaz'a, M. *alöa. 



Peltastisis. 

 P. *tmise}'ialis, P. "'contiifa. 



• This form shows aflmities with the IsiJiruc in the form of its spicules, which are much like those of /sis lnppuris\ but has 

 a rather thin ccenenchyma and evident calyces, characters which allie it with the Mopschhc. Sec Stuui;r, .\Icyonaires provenanl des 

 Campagnes de THirondelle, 1901, p. 39 and Plate Iv, fig. 9. 



