114 ROYAL SOCIETY OF CANADA 



Suborder ^Ionactinellida, or of doul»tful affinity. 

 Genus LASIOTHEIX, Hinde.' 



Spono-es small, depressed oval in outline, the outer surface covered 

 b}' a layer of longitudinally arranged, apparently simple, acerate spicules ; 

 beneath this is another layer of spicules disposed transversely. From 

 the base of the sponge several simple elongated spicules extend. 



The peculiar arrangement of the sui-face spicules in this form indi- 

 cates a probably new genus, 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 sheathing of regular! ar- 

 ranged acerate spicules, and beneath these other spicules, disposed trans- 

 versely, can be distinguished, but Avhether these are really acerate or 

 moditied hexactinellid spicules there is no decisive evidence to show. 

 In one or two instances the spicules appear to be cruciform, and the 

 presence of the long, simple anclioring-si»icules extending from the base 

 of the sponge, precisely as in normal hexactinellids. is a further point in 

 favour of its Ivlonging to this division. 



11. Lasiothrix curvicostata, Hlndc. 



(Fig. 24.) 



The tvp*-' lorm is transversely oval. S mm. in height by 12 mm. in 

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

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

 of pvrites in the body portion, but it is doubtful whether they repi-esent 



mi 



• 



Fk;. 2i.—LasiothrU- rnrrirosfdfa. Natural 

 size and portion enlarged. 



aggregations of spicules or are merely due to the chemical deposition of 

 the mineral, in connection with the presence of organic matter. 



This curious httle sponge, of which few specimens were found, is 

 remai-kable for the strong curved spicules which suppor t its sides, giving 

 1 British Fossil Sponges, Pal. Soc, 1H88, PI. i., fig. 3. 



