BOULDERCLAY OF THE o ROODE KL1F » 



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3. Lithistidae. 



This division is représentée! by the peculiarly irregular spicules with 

 expanded ends to the rays, which belong to the genus Doryderma 

 (figs. 82-88. Similar spicules occur in carboniferous rocks and they 

 are likewise very abundant in cretaceous beds, wherever sponge spi- 

 cules are présent. There is a single elongated spicule (fig. 89), charac- 

 teristic of the genus Carterella. A few nodose spicules (figs. 90-92) 

 are like those of Plinthosella, save that they are 6omewhat smaller. 

 Further there is a single example of a rhizomorine spicule (fig. 93) 

 and a lobate dermal spicule of the Discodermia type (fig. 94). 



4. Hexactinellidae. 



This division is mainly represented by detached six-rayed spicules 

 of the normal type (figs. 95-101). They are of various sizes, but in 

 nearly ail cases the rays have been broken. Thèse spicules probably 

 belong for the most part to Lyssacine sponges, that is, to sponges in 

 which the spicules are not fused into a connected mesh ; of the Dic- 

 tyonine type there are only one or two small fragments of meshwork 

 (figs. 102, io3). There are also fragmentary five-rayed spicules 

 figs. io5-io6) of the same gênerai form as those which stud the surface 

 of the existing Rossella antarctica. Thèse spicules are présent in the 

 Upper Chalk of England and Westphalia. Other minute spicules, 

 likewise five-rayed, are of the scopiform type (figs. 104, 104a) (Besen- 

 gabeln, Vos.). A minute fragmentary spicule is probably the end of an 

 amphidisc flesh-spicule similar to those of the récent genus Hyalonema 

 (fig. 107). 



RADIOLARIA. 



In addition to the sponge-spicules there are a few very fairly pre- 

 served spécimens of Radiolaria, which can be indentified with Dictyo- 

 mitra multicostata, Ziuel, described byZlTTEL from the Upper Chalk 

 (mucronata zone)of Haldem and Vordorf in Westphalia (figs. 108, 109). 

 Zeitschr. d. deutsch. geolog. Gesellsch., Bd. 28, 1876, p. 81, taf. II, 

 figs. 2, 3, 4). 



FORAMINIFERA. 



Thèse organisons are now in the condition ofeasts in silica ; the most 

 abundant form is a species of Globigerina. 



