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A NEW ACTINIAN 



By OSKAR CARLGREN 



Zoological Institute, Lund, Szvcdcn 



The collection of actinians made by the first Johnson-Smithsonian 

 Deep-Sea Expedition to the Puerto Rican Deep, sent to me for report, 

 contained only two species, namely, Leipsiceras (Boloccra) pollens, 

 rather briefly described by McMurrich, and a new species belonging 

 to a new genus, which I am here calling Halcampogetou. 



Family HALCAMPOIDIDAE 

 HALCAMPOGETON, n. gen. 



Body elongated, divisible into physa, scapus, and capitulum. Scapus 

 with 12 longitudinal rows of solid papillae containing very large 

 nematocysts. No sphincter. Tentacles more or less cylindrical, ordi- 

 nary long, hexamerously arranged, few. No siphonoglyphs. Mesen- 

 teries hexamerously arranged, few, probably never more than six 

 pairs. Pennons of the stronger mesenteries concentrated, on slides 

 more or less kidneylike. Parietal muscles strong. At least the eight 

 " Edwardsia "-mesenteries fertile. Nematocysts large. 



The species is separated from all other halcampoidids by the pres- 

 ence of the solid papillae on the scapus and the extraordinarily large 

 nematocysts, especially in the papillae. 



Genotype. — Halcampogetou papillosiis. 



HALCAMPOGETON PAPILLOSUS, n. sp. 



Body cylindrical. Papillae in each row about 20 or more. Tentacles 

 and mesenteries 12. Only the eight " Edwardsia "-mesenteries pro- 

 vided with pennons and fertile. Pennons with numerous partly very 

 ramified folds. Parietal muscles with the strongest folds inward, short 

 but broad folds outward. Nematocysts of the papillae 96-108 x 5-5.5/*, 

 rather numerous, those of the tentacles 58-67 x about 4.5/*, very 

 numerous, those of the actinopharynx partly 53-60 x about 4.5/1, partly 

 38-41 x 4.5-5/x, those of the filaments partly 36-41 x 4.5-5/A, partly 



Smithsonian Miscellaneous Collections, Vol. 91, No. 25 



