24 Br. G. J. Hinde — On a New Fossil Sponge. 



bundle of elongated spicules which extend downwards from the 

 base of the sponge and anchor it in the mud, consequently very 

 different from the horizontal radial disposition of the spicules iu 

 these specimens. Further, if they were the anchoring appendages 

 of hexactinellid sponges, one would naturally expect to find some 

 traces of cruciform or typical six-rayed spicules characterizing the 

 bodies of these sponges, more particularly as the great regularity in 

 which the free radial spicules forming these circular patches have 

 been preserved in their natural position indicates the absence of 

 currents to remove the body-portions from their bases. But on 

 the slabs I have examined, I do not recognize any distinctive 

 hexactinellid spicules. At the same time it is not altogether 

 impossible that these fossils may be a peculiar modification of the 

 anchoring appendage of hexactinellid sponges, and tliis view derives 

 some support from the fact that a species of this group, Cyathospongia 

 reticulata, Walcott, sp., occurs in this Utica Shale, though Mr. 

 Ami has not yet discovered any specimen of it in the vicinity of 

 Ottawa. 



There are however certain recent siliceous Monactinellid and 

 Tetractinellid sponges, inhabiting deep water, which possess basal 

 structures of slender radiating spicules, very similar in character 

 and arrangement to those forming these fossil impressions. Thus in 

 the genus Badiella, 0. Schmidt' (^=Trichostem,ma, Sars^), there is 

 a basal layer of long straight, styliform or pin-shaped spicules 

 radiating from a centre and forming a definite fringe round the 

 sponge, whilst the spicules of the body of the sponge are smaller 

 and less likely to be preserved as fossiL Again in Tethya casula, 

 Carter,^ there is a well-marked basal fringe of spicules, but in this 

 case the spicules have trifid head-rays and consequently differ in 

 character from those in our fossils. As pointed out by Sars, and 

 more particularly by Eidley and Dendy,* the basal fringe of elongated 

 spicules in these sponges serves not so much to anchor the sponge 

 as to support it on the surface of the soft yielding mud of the 

 sea-bottom. 



Thei'e seems fair ground for supposing that these patches of 

 radiating spicules likewise served as basal supports to sustain the 

 sponges, which lived in dense colonies, on the surface of the ooze. 

 Whether these sponges were hexactinellid or monactinellid must 

 for the present remain an open question ; but it may be desirable 

 to give a name to them, and I propose to call them Stephanella 

 sancta.^ 



The specimens were collected by Mr. H. M. Ami from the Utica 

 shale, at Ottawa itself, and in the adjoining township of Gloucester. 



^ Spongien Fauna Atlantischen Gebietes (1870), p. 48, pi. 4, fig. 6. 



^ Eemarkable Forms of Animal Life (1872), pt. i. p. 62. 



3 Ann. and Mag. Nat. Hist. ser. 4, vol viii. (1871), p. 99, pi. iv. figs. 1-9. 



* 'Challenger' Eeport, Zoology, vol. xx. (1877), p. 216, pi. xliii. 



* aTect)a.vr), a wreath, dimin. 



