[lambe] sponges from the ATLANTIC coast of CANADA 207 



are embedded in tlic wall of the .spon^-e, parallel to the; direction of and 

 between the radial tul)es ; their distal ends frequently extend beyond the 

 dermal sui-face. 



Spicules. — (1) TriradiatcSj of the tubar skeleton and of the cortex, 

 Avith long, slender, acutely and sharply pointed, straight rays ; basal ray 

 with an average length of 0-294 mm., lateral rays averaging 0196 ram. in 

 length (Plate III., tig, la) ; many small and immature forms of these 

 spicules also occur. (2) Quadr (radiât es, of the gastral surface, having 

 long, straight, slender apical rays, about 0'222 mm. long and with facial 

 rays similar in form and size to the rays of the triradiates, only rather 

 more slender (Plate III., fig. lb). (3) Oxeote spicules, stout, slightly 

 curved, somewhat obtusely pointed ; length about 0*694 mm., thickness 

 0-013 mm. (Plato HI., tig. *7c). (4) Linear s.jiirules, of the oscular fringe, 

 very slender, straight ; about 1-78 mm. in length and 0-0049 mm. thick. 



Locality. — Between Pictou Island and Cape Bear, in from 46 to 48 

 fathoms, one specimens, in alcohol, J. F. "Whiteaves, 1873 ; eight miles 

 southeast of Bonaventure Island, Gaspé, in 5(j fathoms, stones and coarse 

 sand, one small specimen, in alcohol, J. F. Whiteaves, 1872 ; one specimen, 

 dr}^. Metis, Sir William Dawson. 



Fossil sponges from the Leda clay at Montreal and Ottawa. 



Craniella Logani, Dawson. 



(Plate III., tigs. 8, ^a—i.) 



Tethea Logani, Dawson. 18.57. Canadian Naturalist, vol. ii., p. 421, pi. vii., tia;. 16. 



This sponge, which was described by Sir William Dawson, is one of 

 the most characteristic fossils of the Pleistocene deposits (Leda clay) of 

 Montreal and its immediate vicinity. 



At Sir William Dawson's request, the writer has undertaken a 

 re-examination of authentic specimens furnished by him. 



The type specimens were characterized as consisting of spicules 

 which are pointed at both ends and of two sizes, the larger being f^ths 

 of an inch and the shorter ^th of an inch in length. Sir William 

 Dawson in his description says '-Mr. Bowerl)ank of London, who has 

 kindly examined these curiotis fossils, has no doubt that they belong to 

 the genus Tethea; but does not refer them to any species. The spicula 

 resemble the simple ones of T. /ranium, as figtired by Johnston ; but our 

 fossils do not afford any that are triciispidate." 



A number of specimensof this species have lately been collected from 

 the Leda clay at Ottawa ; they are found preserved in a manner similar 

 to that of the Montreal specimens. 



Many of the specimens are preserved with their spicules .so undis- 

 turbed that it is i^ossible to form a tolerably correct idea of the oriçrinal 

 skeletal arrangement when alive. 



