228 PROCEEDINGS OF THE ACADEMY OP [1886. 



of temperature upon this island, is valuable as indicating so far 

 the conditions of the growth of these and other organisms. 



He says : " The Island is not extreme in its temperature, and 

 the frost does not go very deep into the soil. The lakes freeze 

 in November or December with ice at least a foot in thickness, 

 and remain closed until the end of April. The average tempera- 

 ture during eight years, from 1857 to 1864, was 41-2 Fahr. 

 Average maximum thermometer during the same time 83, 

 minimum 7. In the year 1879, the mean temperature was 40*2 

 Fahr,; highest record August 3, 82; lowest December 22, +4. 

 In Nova Scotia, though that is so much further south, the range 

 is far greater, from +96 to 20 or 24 Fahr., with an annual 

 average of 44." 



The specimens of sponges so kindly forwarded by Mr. MacKay 

 for examination and report, were more or less minute incrusta- 

 tions upon small stones, gathered as above indicated, and 

 belonged to the species SjMngilla lacustris, Auct. ; S. fragilis, 

 Leidy ; S. mackayi, Carter ; Meyenia Jiuviatilis, Auct., and 

 Heteromeyenia pictovensis and Tubella pennsylvanica, Potts. Of 

 these, Spongilla fragilis was by far the most abundant, and our 

 knowledge of its range is thus extended along the Eastern coast 

 of North America from Florida to Newfoundland ; whereas it 

 had previously been traced westwardly to British Columbia 

 near the Pacific Ocean, and more recently has been discovered in 

 Russia, Bohemia and England. Beside the familiar species, S. 

 lacustris, S. fragilis and M. fluviatilis, Tubella pennsylvanica 

 has been rapidly enlarging its borders beyond the narrow limits 

 of its original territorial designation ; while S. mackayi and H. 

 pictovensis had previously been known only from the discoveries 

 of Mr. MacKa}^ in Nova Scotia. 



One other form remains to be described, and at the suggestion 

 of its discoverer it is hereby designated 



Spongilla Nov^ Terk^, n. sp. 



Sponge incrusting ; sarcode of the 3'oung growth, a dense 

 mass of minute spherical cells, embedding slender curving lines 

 of fasciculated skeleton spicules, developing later into a very 

 loose, open tissue, with few connecting spicules. 



Gemmules rather numerous, unusually large, spherical ; chitin- 

 ous coat thin ; " crust " apparentl}'^ wanting. 



Skeleton spicules relatively few, slender, cylindrical, smooth 

 or sparsely microspined ; gradually pointed. 



Dermal or flesh spicules very abundant, minute hirotulates of 

 unequal size ; shafts slender, cylindrical, occasionally spined ; 

 outer surface of rotules dome shaped ; rays prolonged, termina- 

 tions acute ; malformations frequent. Mixed with occasional 

 linear, spined spicules. 



