/' 



New Species of Sponges. 



63 





veiy seldom met with in the fossil condition, but it is not 

 improbable that the delicate film of pyrites, seen in places 

 on the surfaco of the Quebec sponges, may arise from the 

 replacement ol" the flesh-spicules by this mineral. 



Sir J, W. Dawson has already classified and given pro- 

 visional names to the Quebec sponges, and it will therefore 

 be more convenient for me to refer to their generic and 

 specific details under these names. 



Genus, Protospongia, Salter. ' 



Frotoepongia tetranema, Dawson. 



In the one specimen in which the outline of the sponge 

 has been preserved, the body appears to have been elongat- 

 ed oval, measuring about 45 mm. in length by 30 mm. in 

 width. Very probably there was an aperture at the sum- 

 mit, though it cannot now be distinguished. The wall of 

 the sponge appears to have consisted — as in the other species 

 of this genus — of a single layer of cruciform (?) spicules 

 of various dimensions, disposed so as to form a framework 

 with quadrate or oblong interspaces ; the rays of the larger 

 spicules constituting the boundaries of the larger squares, 

 and within these, secondary and smaller squares are 

 marked out by smaller spicules. Judging by the length of 

 the rays of the larger spicules, the larger squares would 

 be about 6 mm. in diameter, whilst the smallest do not ex- 

 ceed 1 mm. The rays of the individual spicules slightly 

 overlap, and it is probable that they may have been lightly 

 cemented by silica at the points of contact. The rays of 

 the largei- spicules are conical, gradually tapering from the 

 central node to the blunted extremity; whilst the rays of 

 the smaller spicules appear to be nearly cylindrical. 



From the base of the sponge, four slender elongated fili- 

 foi'm spicules project. They are approximately cylindrical, 

 pointed at both ends, from .1 to .25 mm. in thickness, and 

 from 50 to TO mm. in length. Their proximal ends are in- 

 serted apparently in the basal wall only of the sponge, and 

 they project in the same direction, though not in lateral 

 apposition with each other. In some specimens their dis- 

 tal ends converge and appear as if united terminally, but 

 this may be merely due to chance overlapping. 



