[lambb] sponges from THE ATLANTIC COAST OF CANADA 199 



Tliecophora semisitheritcs, Vosmaer. 1SS5. The Sponj:;es of the " VVillem Barents 



Expedition, ISKO and IHSl, p. 18, pi. !., figs. Zi, 24, and 



pi. iii., figs. 22-2(i. 

 Tentorium semisii.berites, Vosmaer. 1885. Bronn's Klass. u. Ordn. d. Thierrcichs, 



Porifera, p. ;^29, pi. ii., fig. 4 ; pi. xxi., fig. 19. 

 " " Ridley and Dendy. 1887. Rep. Monaxonida, Zool. Chall. 



Exp., vol, XX,, p. 221. 



Thecophora seniisuberites, Fristedt. 1887. Sponges from the Atlantic and Arctic 



Oceans and the Behring Sea (translation), Vega- 

 expeditionens vetenskapliga arbeten, p. 4'S'A. 



There are twelve specimens of this interesting sponge, three of which 

 are contracted so as to present the "scaly" appearance noticed by 

 Wyville Thompson in some of bis specimens (op. cit.). 



The largest specimen (Plate III., fig. 2) is 28 mm. high, with a dia- 

 meter of 18 mm., and has six oscnlar tubes proceeding from the rounded 

 summit. The number of oscula is variable in different specimens, rang- 

 ing from a single one to as many as six. 



Speaking of the contractile powers of this sponge, Ridley and Dendy 

 {vide supra) say : '• When the specimen is in an expanded condition, the 

 top appears evenly rounded, when, on the other hand, tbe animal is 

 contracted, the top of the sponge owing to the arrangement of the 

 brushes of spicules immediately below the surface, becomes uneven and 

 'scaly' in appearance. Evidently, when living, the sponge possesses 

 great power of contractility, a power which would appear to be shared 

 in large measure by the oscular tube." 



Measurements of the spicules taken from the St. Lawrence speci- 

 mens gave the following results : — 



Tjjlosiyli from the main fibres ; maximum size 2-4 by 0*02 mm. 

 (Plate III., tigs. 2a, 'lb). 



Tylostyli from the cortex of the top ; variation in length from 0'274 

 to 0-670, and in thickness from 0-013 to 0-018 mm. (Plate III., %. 2c). 



Localities. — Northern part of the Gulf of St. Lawrence, in from 20 

 to 96 fathoms, twelve specimens, in alcohol, J. F. Whiteaves, 1871-2-3. 

 Eight miles southeast of Bonaventure Island, Gaspé, in 56 fathoms, 

 stones and coarse sand, one specimen, in alcohol, J, F. Whiteaves, 1872. 



Distribution. — Gulf of St. Lawrence (J. F. Whiteaves) , off ISTova 

 Scotia (Challenger) ; Batîin Bay, Omenak Bay. west and east coast of 

 Greenland (Fristedt) ; Greenland (Schmidt) ; northeast coast of United 

 States (Verrill). 



Foreign distribution. — Off the Shetland Islands (Wyville Thompson) : 

 lat. 72° 36'5 N., long. 34° 57'5 E. (Vosmaer) ; Inaccessible Island (Chal- 

 lenger) ; European Arctic Sea and Barent's Sea (Fristedt). 



