PLATE XL 



Page 

 Fig. 1. Phymatella retindata, Hinde. A club-shaped example, imperfect at the base. 



Two-thirds the natural size. From the Upper Chalk at Flamborough, York- 

 shire 59 



Fig. 1 a. The same. Portion of the surface of another specimen from Flamborough, 

 shoMring, after treatment with acid, apertures of the canals which open at the 

 surface and traces of the interior spicules, which hare been in part replaced by 

 calcite. Enlarged eight times. 



Fig. 1 b. The same. Microscopic section of the interior, showiag traces of the spicules. 

 The outline of the spiciile.s is less definite than represented. Enlarged twenty- 

 four times. Drawn from a transparent section. 



Fig. 2. Phymatella nodosa, Hinde. An imperfect specimen from the Upper Green Sand 



at Warminster, Wiltshire. Natural size 60 



Fig. 2 a. The same. Portion of the outer surface, showing traces of Tetracladine spicules. 

 Enlarged sixteen times. 



Fig. 3. Callopegma obconicum, Hinde. A specimen inclosed in a flint. From the Upper 



Chalk of the South of England. Natural size 61 



Fig. 3 a. The same. A vertical median section of a specimen, enlarged one and a half times, 

 showing the general disposition of the canals and the spicular mesh. 



Fig. 3 6. The same. Portion of the interior spicular mesh of Za. The spicules have been 

 replaced by iron peroxide, and the nodes formed by the junction of the spicular 

 rays are consequently imperfect. Enlarged thirty-two times. 



Fig. 4. Callopegma ficoideum, Hinde. A specimen inclosed in a flint. From the Upper 



Chalk at Guildford, Surrey. Natural size 61 



Fig. 4 a. The same. Portion of the outer surface of fig. 4, enlarged sixteen times, showing 

 the extended heads of compound trifid spicules of the dermal layer. 



Fig. 4 6. The same. A fragmentary spicule of the interior skeleton. Enlarged sixteen 

 times. 



