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Canadian Record of Science. 



1 



This species appears to have been the prevailing form at 

 Mdtis. Four specimens have been sent to me; in two of 

 those the spicuhir frame-work of the body of the sponge re- 

 tains in phicos its natural arismgement; in the other two 

 the frameworli has been almost entirely broken up, and its 

 constituent spicules irregularly mingled and compressed 

 together. But in every specimen there are four anchoiing 

 spicules occupying the same relative position to the frame- 

 work or body-wall of the sponge, thus clearly showing that 

 they are essential to the species. In the spicules of the 

 body-wall only four transverse rays can be distinguished, 

 but it is quite possible, as already mentioned, that a fifth 

 ray may have been present. On one of the rock-slabs 

 there is a detached spicule in which the fragmentary 

 stump of a fifth ray can be clearly seen projecting from 

 the central node of the transverse rays. The rays in this 

 spicule aie unusually long, one can be traced for 30 mm. 



There can be no hesitation in placing this form in the 

 genus Protosponyio, since the same arrangement of the 

 spicular mesh-work is present in it as in the type of this 

 genus. In no other examples of the genus, however, has 

 the presence of anchoring spicules been recognized, owing, 

 no doubt, to their impeifect state of preservation, and this 

 feature may now be reckoned as one of the generic 

 charaners. ' . 



There are also differences of opinion as to the character 

 of the spicular mesh-work and the systematic pofsition of 

 Protospongia, and fresh light on the points contested is 

 afforded by these Quebec specimens. It has been doubted 

 whether the body-wall of the sponge merely consisted of a 

 single layer of spicules, or whether this layer corresponded 

 to the dermal layej- in other sponges of this gi'oup, and, as 

 in these, was supplemented by an inner spicular skeleton. 

 The.evidence of the Quebec specimens favors the view that 

 the body-wall of the sponge consisted only of a single layer 

 of spicules. Various opinions have likewise been held as 

 to whether the body-spicules were free, and merely held in 

 their natural positions by the soft animal tissues, or 



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