j,S<S 'ENDEAVOUR" SCIENTIFIC RESULTS. 



in R. paucispinus the auxiliary spicules approximate in length 

 to the principal styli they are here very much longer. 1 he 

 absolute dimensions of both the principal and auxiliary styli 

 differ to a notable extent in the different varieties, but it is a 

 peculiar circumstance, that their variation in the matter of 

 stoutness proceeds, throughout the stories, with a certain 

 degree of concomitance, the range of variability of the aux- 

 iliary spicules in this particular being relatively somewhat less 

 than that of the principal spicules. For example, in the 

 variety favosiAs, where the spicules attain their greatest size, 

 the principal styli are 13 >i, the auxiliary 9 to 10 jt in diameter, 

 a difference in stoutness of 3 to 4 ;< separating them ; whereas 

 at the other end of the series in the variety anchoraius the 

 principal styli are 6 ;*, the auxiliary, 5 )i in diameter, with a 

 difference of only i \i between them. The correlation of the 

 two spicule-forms in this way would seem to imply a kind of 

 genetic relationship between them — an implication which is 

 further heightened by the fact that spicules similar to those 

 within the fibres are also of frequent occurrence scattered 

 amongst the auxiliary spicules in the ground substance, and 

 by the fact, moreover, that in R. paucispinus the two spicule- 

 forms agree in the matter of length. The argument that the 

 spicules, here termed auxiliary, are derivatives of the principal 

 spicules, cannot however, be sustained, although instances are 

 not wanting of sponges in which the latter spicules show a 

 tendency to resolve into two forms, e.g., Ophlitaspongia 

 axincUoides, Dtndy. Their independence is proven in the pre- 

 sent species not only by their difference in shape, but also by 

 their different modificational tendencies. Abnormalities of the 

 principal styli appear to be invariably strongylote, whilst those 

 of the auxiliary (and special dermal) styli are oxeote. As in R. 

 paucispiyius, so also in this species, it is obvious that the 

 dermal styli are simply specialised auxiliary spicules. 



Echinoncina iypicum, Carter, has not }et been sufficiently 

 described to enable one to recognise it with certainty, though 

 Dendy has pointed out its close agreement with other sponges 

 of the present series. Concerning those specimens referred 

 to bv Dendy, in which he failed to observe toxa, nothing can 

 be said with certainty, but in view of the fact that toxa are 

 abundant in all the varieties here described, it is highly 

 probable that they represent another species. Echi)wnenia 

 iypicum was recorded by Carter from South and South-West 

 Australia, and in regard to external form was described as 

 "shrubbv, cauliculate, more or less compressed, bunch-like or 

 clustral, consisting of a great number of digital more or less 

 branched stalks spreading upwards from a contracted sessile 

 base; branches cylindrical, round, or slightly compressed, 

 more or less sub-divided, terminating in obtuse round ends." 



