CEATICULAEIA.— SPHENAULAX. 95 



calcite, and is therefore indistinct, but in one specimen from the Isle of Wight the 

 siliceous skeleton is partly retained. The interior mesh of the wall is more irregular 

 than in the Jurassic forms of this genus ; the spicular arms or rays are about "05 mm. 

 in thickness, and the length from centre to centre of the nodes is '25 mm. The 

 dermal layer of the outer surface of the wall has a stellate appearance ; the nodes of 

 the spicules are flattened, and numerous rays extend from each ; besides the inter- 

 spaces between the spicular arms, there are also minute circular apertures in the 

 dermal layer. 



This species is abundant and occurs in all the divisions of the Chalk series, from 

 the Upper Green Sand to the Upper Chalk. Toulmin Smith describes this species 

 as "having a deep primary fold of regular quadrilateral and rectangular form. 

 Usually more or less oblong, and arranged in tesselated figure." I cannot ascertain 

 that the walls are at all folded, but merely penetrated with numerous canals on both 

 sides, which do not extend quite through the wall but terminate bluntly. T. Smith 

 does not mention the difference between the solid nodes of this species and the 

 lantern-nodes of Ventriculites. 



Distribution. Craie Chloritee : Honfleur, Vaches Noires {Tesson coll.). Chalk 

 Marl : Ventnor, Isle of Wight. Grey Chalk and Lower Chalk : Dover, Folkestone. 

 Upper Chalk : South of England {Toulmin Smith and Mantell's coll.). 



Ceaticulakia subseeiata, Roem,er, sp. 

 1840. Seyphia subseriata, F. A. Roemer, Verst. d. Nordd. Kreide, p. 9, t. 3. f. 8. 



Sponge consisting of bifurcating cylindrical branches, 15 to 22 mm. in thickness ; 

 the walls are 2 to 2-5 mm. thick. The canal-apertures are disposed in vertical and 

 transverse rows ; they are -75 mm. wide, and nearly the same distance apart from 

 each other. Spicular mesh of the interior irregular in disposition. A single frag- 

 mentary specimen is in the collection, which appears to agree with Rcemer's species. 

 From Craticularia Fittoni it is distinguished by the smaller dimensions of the 

 branches and canals. 



Distribution. Upper Chalk : Norwich [Bayfield coll.). 



Genus SPHENAULAX, Zittel, 1877. 



Sphenaulax costata, Goldf. sp. 



1833. Seyphia costata, Goldf. Petref. 1 Th. p. 6, t. 2. f. 10. 



1877. Sphenaulax costata, Zitt. Studien, I Ab. p. 47 ; Neues Jahrbuch, p. 35G, t. 2. f. 3, 



and p. 709. 



1878. Sulcispongia incisa, colliciaris, rimosa, viaria, semiclathrata, Quenst. Petref. Bd. 5, 



p. 83-90, t. 118. f. 8-lG. 



Distribution. Upper Jura : Engelshardt, Heuberg. 



