Nodules of the Trimmingham Chalk. 393 



no reason for supposing that they belong to a Geodia, though 

 they might very well be derived from some not distantly 

 related sponge, in which case the large conical spicule which 

 we have named Rhopaloconus may have filled the same place 

 in it as the globates in Geodia. Perhaps fig. 54 should be 

 associated with this group. 



Scoliorhaphis ? (PL XX. fig. 66.) 



This undulating uniaxial spicule may be derived from a 

 Scoliorhaphis. 



Hexactinellida. 



DlCTTONINA. 



Separate octahedral knots, and fragments of Euretid network, 

 occur pretty frequently in the flints. Numerous sexradiate 

 spicules are also found, and may very possibly have been de- 

 rived from the dermis, roots, and other pai-ts of the Dictyonine 

 sponges, which are indicated by the fragments of network. 



Fig. 69 is a form resembling one of the commonest spicules 

 in Euplectella. 



Figs. 58, 60, and 65 are evidently anchoring-spicules, the 

 two latter terminating in a four-rayed, the first in a double- 

 rayed, head. In fig. 60 the four rays are all on one side of 

 the head. The shafts are smooth and not spined. Fig. 68 

 is also apparently an anchoring spicule. 



Fig. 62 is possibly part of a spicule which when complete 

 resembled those which Carter describes as forming a fringe 

 to the edges of the tubes in Myliusia Grayi. 



Fig. 6'6 is probably a dermal spicule. 



Figs. 57 and 61 are small spicules of indefinite nature. 



Figs. 67 and 67a, the end probably of one of the small 

 rotulate spicules of a Hexactinellid. 



[Casts of Foraminifera. 

 Zittel, Cceloptychmm, Taf. v. figs. 11, 12, and 17. 



Fig. 50 looks like a new form of spicule, for which one 

 might find a name meaning " dumb-bell form ;" as a sponge- 

 spicule, indeed, we find it regarded in Zittel's monograph on 

 Conloptychium. The occurrence of similar forms, but possess- 

 ing three globular swellings instead of only two (fig. 49), 

 and these not always in a straight line (fig. 48), naturally 

 suggests doubts as to its spicular character, and leads one 

 rather to see a resemblance to Foraminifera, such as the Nodo- 

 sarina. Nor can there be any doubt that they are simply 



Ann. & Mag. N. Hist. Ser. 5. Vol. vi. 28 



