TEACHrsmiA. 189 



of minute irregular three-rayed spicules closely intermingled ; amongst these the 

 pitch-fork forms are conspicuous. 



Listrihition. Cretaceous. Upper Green S:md : Vaches Noires, near Havre. 



Genus TRACHYSINIA, Hinde, n. g. 



Sponges either single or growing in bushy masses. The individual spongites are 

 depressed, cylindrical, with uneven, nodose surfaces ; the summits generally inflated. 

 The cloacal tube is subcylindrical, shallow, or extending to some depth ; in some 

 instances open radiating canals extend from its margins. The interior canals appear 

 to be but slightly developed, the circulation taking place in the interspaces of the 

 coarse fibrous mesh. • 



The fibres are composed of relatively large three- and perhaps four-rayed spicules 

 heterogeneously mingled with smaller forms. In some places the rays of the larger 

 spicules are in the axis of the fibre, but this disposition is not so general as in 

 Sestrostomella. The margins of the fibre show lines of sinuous spicules as in this 

 last-named genus. 



The minute fibrous structure of this genus shows its alliance to Sestrostomella, 

 from which it is distinguished by the tubular character of the cloaca and the nodose 

 mode of growth. In general form it resembles Corynella, but the spicular structure 

 distinguishes it from the typical forms of this genus. It appears to me not unlikely 

 that the minute structure of some of the Jurassic species of Corynella, such as 

 C. Quenstedti, Zitt., for example, will be found to correspond with that of the 

 present genus. 



Trachtsinia aspera, Hinde, n. sp. (Plate XXXV. figs. 6, 6 «, 6 h.) 

 Sponge forming a mass, 60 mm. high by 75 wide, of depressed cylindrical indivi- 

 duals, from 26 to 37 mm. in thickness. The outer surfiice is very uneven and covered 

 with nodose excrescences. The summits are inflated with occasionally slightly 

 elevated necks to the cloacal apertures, which are from 7 to 12 mm. in width. The 

 surface exhibits irregular apertures between the fibres. 



The fibres, as seen in a transverse section, vary from "14 to '5 mm. in width ; the 

 largest spicular ray observed is "2 mm. in length by -04 mm. in width. 



Distribution. Middle Jura : Couche a polypiers — Hanville, near Caen (coll. Tesson). 



Teachysinia solitaeia, Ilinde, n. sp. (Plate XXXVI. fig. 9.) 

 Sponge simple, with a short cylindrical body supported on a compressed stem. 

 Surface with nodose excrescences. The summit is truncate, slightly concave, the 

 cloaca is shallow, with canals radiating from the margins ; it is about 5 mm. wide. 

 The fibres are about -2 mm. wide. The spicular structure has not been ascertained. 



