388 Mr. W. J. Sollas on the Flint 



In the recent sponge the swollen part of the fourth arm is 

 ornamented by fine longitudinal lobations, which are absent 

 in the fossil fragments. The finely branched ends of the 

 three other arms have disappeared in the fossil spicules as a 

 consequence of fossilization. To indicate the alliance between 

 the recent and the fossil forms, and, at the same time, to 

 denote their difference, I have employed the word /co/x^os for 

 KaWos in the construction of the generic name. 



No dermal spicules have been seen which could be consi- 

 dered strikingly similar to K. cidaris. Fig. 24 is a curious, 

 finely tuberculated little disk ; but it has no shaft, and cannot 

 be referred here. 



Megamorina. 



Podapsis cretacea and parva. 

 (PI. XIX. figs. 18 and 23, 25 and 26.) 



Carter, on Fossil Sponge-spicules, loc. cit. p. 118, pi. x. figs. ; Wright, 

 Irish Cret. Microzoa, Belfast Nat. Field-Club, ser. 2, vol. i. pi. iii. 

 figs. 2 and 3. 



Figs. 18 and 23, 25 and 26 represent the skeletal corpus- 

 cles of a Lithistid evidently allied to Lyidium torquila, Sdt. 

 They appear to be much too small to be referred to any of 

 Zittel's species of Megamorina from the chalk ; and we provi- 

 sionally give them a distinct name, the curious foot-like shape 

 of the articular surface at the end of their simple unbranched 

 rays suggesting the term Podapsis. They differ themselves 

 widely in size ; and the larger forms appear to be also simpler 

 than the smaller ; so that we may distinguish them as species, 

 the larger as P. cretacea, the smaller as P. parva. In Zittel's 

 Doryderma {D. dichotoma, Phil.) a bifurcated trifid spicule is 

 present, somewhat similar to that of fig. 19, which we place 

 here for comparison. 



Carter, who was the first to identify Megamorine corpuscles 

 in the fossil state, says of those he found in the Haldon 

 Greensand : — " many . . . are almost facsimiles of Schmidt's 

 figures of Lyidium torquila, obtained by M. de Pourtales in 

 270 fathoms off the island of Cuba (Atlant. Spong. Fauna, 

 p. 84)." 



Rhizomorina. 



Corallistes cretaceus. (PI. XIX. fig. 4.) 



Carter, Fossil Sponge-spicules, loc. cit. ; Zittel, Cceloptychium, Taf. vi. ; 

 Wright, Irish Cret. Microzoa, loc. cit. 



This trifid spicule with bifid arms is a very common form ; 

 it is probably derived from the dermal skeleton of some 



