114 



KOYAL SOCIETY OF CANADA 



Suborder ^foNACTiNELLrDA, or of (louhtf'ul affinity. 

 Genus J.ASIOTHRIX, Iliiide.' 



Sponyos small, depressed oval in outline, the outer surface covered 

 by a layer of loniritudinally ari-anifod, apparently simple, aecratc spicules ; 

 beneath this is another layer of spicules disposed transversely. From 

 the hasc of the sponnv several simple elono-ated spicules extend. 



The pecidiar ari'anu;ement of the surface s])icules in this form indi- 

 cates a probably nt'W i;enus, but in its present condition one cannot tell 

 with certainty whether it is monactinellid or hexactinellid. The outer 

 surface seems to have been invested with a sheathini;- of rcii-ularls ar- 

 ranu'ed acerate spicules, and beneath these other spicules, disposed trans- 

 versely, can be tlistin«fuished. but whether these are really acerate or 

 modified hexactinellid spicules there is no decisive cvideiu-e to show. 

 In one or two instances the s])icules appear to be crucifoi-m, and the 

 presence of the lonir, simple anchorinii;-siticules extendinii; from the base 

 of tlu' sponuje, ])recisely as in normal hexactinellids. is a further point in 

 favour of its belonii'inii' to this division. 



11. — Lasiothkix cukvicostata, Jlindc. 



(Fig. 24.) 



The type form is t ransvei'sely oval. S mm. in height by 12 mm. in 

 width, the anchoring-spicules can be traced to a length of 15 mm. from 

 the body. The summit is rounded. There are some nodular elevations 

 of pyi'ites in tlu' body portion, but it is doubtful whether they represent 



Fid. '24.~ LasiothrU' ciirricosfiitd. Natural 

 fsize and i)ortioii eiiJarKt'tl. 



jiggregations of spicules oi- are merely due to the chemical deposition of 

 the mineral, in connection with the presence of organic niattei'. 



This curious little sponge, of whi(di few sj)ecimens were found, is 

 remai'kable for the strong curved spicules which support its sidcis. giving 



I British Fossil Sponges. Pal. Soc, 18.S8, PI. i., lig. a. 



