CEPHALITES. 121 



Cephalites paradoxus, Toulm. Smith. 



1848. Cephalites paradoxus, T. Smith, Ann. & Mag. Nat. Hist. 2nd ser. vol. i. p. 283, 



t. 14. f. 3. 

 1878. Cephalites paradoxus, Zitt. Studien, I Ab. p. 52 ; Neues Jahrbucli, p. 363. 



Sponges funnel-shaped, supported on a short stem with diverging roots. An 

 average specimen is 80 mm. in length, and 34 in width, at the summit. The wall 

 varies from 4'5 to 8 mm. in thickness. The wall-ridges of the outer surface are 

 2 mm. in width ; they anastomose with each other so as to leave irregular inter- 

 spaces. The interior surface appears to be formed by straight longitudinal ridges 

 and furrows. The disposition of the interior plaits of the wall appears to be the 

 same as in the preceding species. 



Distribution. Upper Chalk: Kent {coll. T. Smith). 



Cephalites BsNETTiiE, Mantel!, sp. 

 1822. Ventriculites Benettice, Mant. Foss. of the South Downs, p. 177, t. 15. f. 3. 



Sponges funnel-shaped, with divergent roots, apparently springing from the base of 

 the funnel. The type specimen is 59 mm. in length and 35 in width ; the wall at the 

 summit is 9 mm. in thickness. 



The outer surface is composed of anastomosing ridges, about 2 mm. in width, 

 disposed so as to leave oval or irregular interspaces from 2 to 6 mm. in length ; the 

 interior surface of the wall appears to possess circular canals about 2 mm. in diameter. 

 The interior plaits of the wall are not shown. 



So far as can be judged from the condition of the specimen, this species differs 

 from C. 2^arado.vns principally in the characters of the interior surface of the wall. 

 Mantell's figure is a very rude and not altogether accurate representation of the 

 original, which is in the Museum. 



Distribution. Upper Chalk : Lewes, Sussex (coll. Mant.). 



Cephalites alternans, Toulm. Smith. 



1847-48. Cephalites alternans, T. Smith, Ann. & Mag. Nat. Hist. 1st ser. vol. xx. t. 7. f. 2, 

 and 2nd ser. vol. i. p. 283, t. 14. f. 4, 5. 



Toulmin Smith's type of this species is a small funnel-shaped sponge, 28 mm. in 

 length by 20 in width ; the thickness of the wall is 6 mm. The outer surface is 

 apparently composed of reticulating ridges, about 1-5 mm. in thickness, with irregular 

 interspaces ; the interior surface has ovate canals, about 1-8 mm. in diameter, disposed 

 in quincunx. The plaits of the interior of the wall are disposed in somewhat 

 irregular folds, as shown in Smith's figure, /. c. vol. xx. t. 7. f. 2 ; the simple plait 

 is about 1 mm. in thickness. The distance between the octahedral spicular nodes 



K 



