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ROYAL SOCIETY OF CANADA 



and flattonino- the spicules are usually much displaced. Within these, 

 secondary and smaller squares are marked out hy smaller spicules. 

 Judging W the length of the rays of the larger spicules, the larger squares 

 woukl he ahout -4 mm. in diameter, whilst the smallest do not exceed 



-f 



+ 



+ 



4- 



Ym, •ii.—Protos23ongia fefranema. Primury, secondary and 

 tertiary cruciform spicule.s, x 5. 



1 mm. The rays of the individual spicules seem to have heen united 

 merely by t he animal matter, and not by a silicious cement. The osculum 

 is protected l)y defensive spines (Fig. 4), and in young specimens these 

 are often very" numerous. The rays of the larger spicules are conical, 

 gradually tapering from the central node to the pointed extremity ; 

 whilst the rays of the smaller spicules appear to be nearly cylindrical. 



From the base of the sponge, four slender, elongated, filiform rods 

 project. They are approximately cylindrical, pointed at both ends, very 

 slender, and from 50 to 70 mm, in length. Their proximal ends are 

 inserted apparently in the basal part only of the sponge. In perfect 

 specimens they are seen to approach and cross each other in the middle, 

 and then to diverge, tinally again approaching and forming a loop with 

 a minute central point. So many examples of this structure have now 



.^^^^"-^ 



Fig. i.—Proto.Hjiongiatetiamiiia. Osculum enlarged 



and surrounded by minute spicule.s. Fn;. .5.— Anchoring-rods. 



been found that there can be no doubt as to its true nature, though in a 

 few instances the loop has broken asunder, leaving the rods free. Even 

 in this case, however, they show their curved ends (Fig. 5). 



