" 



LIBRARY 



THE CANADIAN FIELD-NATUR^LTS'f' 



# 



VOL. XXXV. 



GARDENVALE, QUE., September 1921 



No. G 



OxN A NEW HELIOZOON FROM VANCOUVER ISLAND 

 By Chas. H. O'Donoghue, D.Sc, F.Z.S., 



Professor of Zoology, University of Manitoba. 

 (Fi'om the Biological Station, Nanaimo, B.C.) 



On the 25th of May Mrs. Eclitli Berkeley 

 brought in some water, mnd and debris 

 from a small pond near the top of a hill- 

 above Hammond Bay Lagoon, about 420 

 feet above sea level. In this she noticed 

 a very large Heliozoon, which she kindly 

 handed to me for. examination. 



The pond is quite small and shallow, 

 surrounded by a close gl'0^^i:h of alders, 

 and is apparently permanent. It contains 

 a plentiful supply of several species of 

 Algae (Spirogyra, etc.), numerous fly 

 larvae, beetles and larvae, Copepods, Cla- 

 docera, and Hydra vindis and a number 

 of flagellate forms. 



The available literature has not yielded 

 a description of a similar form nor is there 

 anything like it in Wailes' excellent mono- 

 grapli number of this order (1) or Leidy's 

 account of the Freshwater Rhizopoda of 

 North America. As the present organism 

 is remarkable in several respects, it seems 

 worthy of putting on record. 



The animal is of very large size and ap- 

 pears to the naked eye as a briglit green 

 sphere with a hyaline cover 2mm. in 

 diameter; indeed, it was so large that it 

 was at first thought that it miglit be a 

 colony. Closer examination showed that 

 this was not the case and that it was a 

 solitary form, so that it is probably the 

 largest Heliozoon known, the only one ap- 

 proaching it being Acirnosphaerinm 

 eichhornii, which may attain a diameter' of 

 1mm. It belongs to the sub-order Chalaro- 

 thoraca in which the largest member is 

 probably Raphidiophrys viridis, which 



(1) The British Freshwater Rhizopoda and 

 Heliozoa, by J. Cash, G. H. Wailes and J. Hop- 

 kinson. Vol. V, Heliozoa, by G. H. Wailes, Lon- 

 don, Ray Society, 1921. 



may reach 90 micra or the colony 190 micra 

 The present species is then approximately 

 22 times the diameter of the individual 

 or 10 times that of the colony. 



The body is spherical and measures 

 1.486mm. in diameter; it is enclosed in a 

 mucilaginous envelope .540mm. thick. Be- 

 yond this again the stiff pseudopodia ex- 

 tend 1.892mm. so that the total diameter 

 of the whole organism is 3.918mm. The 

 pseudopodia are quite numerous, reg- 

 ularly arranged and project to an equal 

 distance on all sides. They appear quite 

 stiff and were not seen in active move- 

 ment. The mucous envelope was only 

 slightly granular and contained a few 

 tiny spherical algae and still fewer some- 

 what spindle-shaped ones. On the outside 

 of it were sparsely scattered tiny curved 

 spicules apparently siliceous and some- 

 what pointed at each end. The envelope 

 ran up a short distance on each pseudo- 

 podium. 



pjg. 1._ RAPHIDIOPHRYS MAGNA, general 

 view. The darker area situated slightly excen- 

 tricaily represents the nucleus and endoplasm. 

 A. A small portion of the symbiotic Algae 

 to show their characteristic dendritic arrange- 

 ment. 



