Some Canadian and Alaskan Arctic Sponges 



By Arthur Dendy, D.Sc, F.R.S., 



Professor of Zoology, King's College, University of London, 



and 

 Leslie M. Frederick, M.Sc, 



Late Harold Bow Research Student in King's College, London, 



The collection of American Arctic Sponges submitted to us for examination 

 and report contains little of very special interest, all the identifiable species 

 being already well known arctic forms. Perhaps the most interesting point is 

 the discovery of the fact that the common Ficulina ficus forms part of the food 

 of the seal Erignathus barbatus (Erxleben). 



LIST OF SPECIES REPRESENTED 



Order Calcarba 



Family GRANTIIDAE 



Leucandra sp. 



Order- Tetraxonida 



Suborder Sigmatotetraxonida 



Family HAPLOSCLERIDAE 



Reniera gracilis (Miklucho-Maclay) Dybowski 



Halichondria panicea Johnston 



Family DESMACIDONIDAE 



Phakellia variabilis (Vosmaer) 



Family CLAVULIDAE 



Ficulina ficus (Linn^) Gray 



Polymastia mammillaris (0. F. Mueller) Bwbk. 



DESCRIPTIVE AND CRITICAL REMARKS 



Leucandra sp. 



The single specimen, which is rather badly preserved, is attached to branches 

 of seaweed. : It forms an erect, nearly straight, cylindrical tube, about 25 mm. 

 long and 3 • 5 mm. in diameter, terminating above in an osculum provided with 

 a short peristome; the wall of the tube is about 0-83 mm. in thickness. Colour 

 in spirit light brownish-grey, texture soft and fragile. 



There is a thin dermal cortex, about 0-065 mm. in thickness, and a very 

 slight gastral cortex about • 05 mm. in thickness. Thickly scattered dermal 

 pores lead into wide, more or less lacunar, inhalant canals which penetrate 



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