190 CALCAEEOUS SPONGES. 



This species differs from the preceding in its simple mode of growth and the more 

 delicate character of the fibres. 



Distribution. Middle Jura : Couche a polypiers — Ranville {coU. Tesson). 



Trachtsinia minok, Hinde, n. sp. (Plate XXXVI. fig. 10.) 



Sponges forming small groups of subcylindrical individuals, from 10 to 18 mm. in 

 thickness, frequently united laterally. The outer surface is uneven and perforated 

 with large and small irregular apertures. The summits are usually inflated ; the 

 cloacal aperture is from 3 to 5 mm. in width and has several well-marked open 

 canals radiating from its margin. The fibres, as seen in a transverse section, are 

 about 2 mm. in width ; the spicular structure resembles that of T. asjiera, but in 

 the specimen examined marginal sinuous spicules are not present. 



Distribution. Middle Jura: Couche a polypiers — Lebisey ; Ranville, near Caen 

 (coU. Tesson). 



Genus BLASTINIA, Ziffel, 1878. 



Blastinia costata, Goldf. sp. 



1826-33. AchiUeum costatum, Goldf. Petref. 1 Th. p. 94, t. 34. £. 7. 

 1878. Spongites costatus, Quenst. Petref. Bd. 5, p. 221, t. 125. f. 19-23. 

 1878. Blastinia costata, Zitt. Studien, III Ab. p. 42. 



Distribution. Upper Jura: Eanden ; Nattheim, Wiirtemberg. 



Bl^vstinia alata, Quenst. sp. 



1858. Sponyites alatus, Quenst. Der Jura, p. 699, t. 84. f. 28, 29. 

 1878. Sponuites alatus, Quenst. Petref. Bd. 5, p. 222, t. 125. f. 24, 25. 

 1878. Blastinia alata, Zitt. Studien, III Ab. p. 42. 



In a vertical microscopic section of a specimen from Nattheim the fibres bounding 

 the circular pores are from "09 to T2 mm. in thickness; their structure is, to a great 

 extent, obliterated, but here and there clearly marked portions of three-rayed spicules 

 can be distinguished. 



Distribution. Upper Jura : Nattheim, Wiirtemberg. 



Genus SYNOPELLA, Zitfel, 1878. 



SynopelljV prLVi>'AKiA, Goldf. sp. (Plate XXXVI. fig. 1.) 

 1826-33. Manon pulvinarium, Goldf. pars, Petref. 1 Th. p. 2, t. 29, f. 7 a, b (non t. 1. 



f.6a,b). 

 1864. Tremospungia puhinaria, F. A. Koemer, Pal. Bd. 13, p. 40, t. 14. f. 8. 

 1878. Synopella pulvinaria, Zitt. Studien, III Ab. p. 43. 



The sponges from the Lower Green Sand at Farringdon, which I refer to this 



