200 CALCAEEOUS SPONGES. 



I have previously compared the structure of this species to that oi Sestrostomella* , 

 but on further examination I find that the fibres of the interior of the wall are built 

 up of filiform spicules, though it is not unlikely that the dermal layer may be com- 

 posed of relatively large three- or four-rayed forms. 



Distribution. Lower Green Sand : Farringdon ; Upware. 



Raphidonema stellatum, Goldf. sp. 



1826-33. Manon stellaium, Gold. Petref. 1 Th. p. 3, t. 1. f. 9. 



1871. Stellisjiongia Goldfussiana, Gein. Pal. Bd. 20, p. 31, t. 6. f. 4-7. 



1878. Manon peziza stellatum, Quenst. Petref. Bd. 5, p. 3G1, t. 132. f. 34'. 



1883. Elasmostoma stellatum, Dua. Pal. Bd. 29, p. 40, t. 37. f. 1, 2, 6, and t. 38. f. 1, 2, 3. 



Sponges growing in thin expansions or funnel-shaped. The walls are from 2 to 

 nearly 4 mm. in thickness. The oscular apertures are about '5 mm. wide, and are 

 either on the upper or under surface of the wall. The fibres bordering the apertures 

 have a stellate arrangement. The opposite surface of the wall exhibits an open 

 network of fibres. 



As seen in a transverse microscopic section, the fibres are from "12 to -25 mm. in 

 width ; they are mainly composed of slender, filiform, irregular, three-rayed spicules. 

 The forms which Dunikowski refers to as " Stabnadeln " appear to me to be more 

 probably fragments of three-rayed spicules. 



The thin walls and stellate character of the oscular surface readily distinguish 

 this species. 



Distrihution. Cenomanian : Essen, Rhenish Prussia. 



Raphidonema Fakringdonense, Sharjje, sp. (Plate XXXVII. figs. 5, 5 a, 5 h.) 



1864. Manon Farringdonensis, Sharpe, Quart. Joum. Geol. Soc. vol. x. p. 196, t. 5. f. 5, 6. 

 1874. "^ Chenendopora funyiformis, Davey, Trans. Newbury Field-Club, p. 13. 

 1878. Catagma Farringdonense, Sollas, Ann. & Mag. Nat. Hist. vol. ii. p. 362. 

 1878. Pharetrospongia Farringdonensis, Zitt. Studien, III Ab. p. 46. 



Sponges cup- or funnel-shaped, free or attached by a spreading base, generally to 

 other sponges. Very variable in size ; a small individual measures 30 mm. in height 

 and width, whilst a large specimen is 90 mm. in height by 120 in width at the 

 summit. The wall varies from 7 to 17 mm. in thickness. The outer surface of the 

 cup is very uneven, and frequently covered with large nodose excrescences. In some 

 examples the fibres of this surface are finer and closer arranged than in the interior ; 

 but, as a rule, there is scarcely any difi"erentiation in their character. The interior of 

 the cup has a very varying aspect in difierent specimens. In some examples it is 

 coarsely fibrous and exhibits ill-defined apertures of numerous canals, about 1 mm. 

 wide, either irregularly distributed or with a partially horizontal arrangement. 



* Annals & Mag. Nat. Hist. 5th ser. vol. x. p. 203. 



