Plate X. — Enlarged details. 



Fig. 1. — A wax squeeze from a portion of the impression of the abactinal 

 surface, showing- accurately the relation of the plates ; x 3 diameters. 

 Compare Forbes, pi. xxiii, fig. 7. cent, small plates of the central area. 

 fr. a frame-plate, per. plates of the perradial area. s. suture between two 

 of the latter, apparently crenulate. gr. portion of left anterior subvective 

 groove, col. columnal lying on matrix that fills a part of this groove. 



Fig. 2. — The peristomial region of the internal cast, slightly diagrammatised, and 

 seen from right posterior interradius ; x 2 diam. s't.c. a depression where 

 a semicircular ridge on the inside of the test is supposed to have supported the 

 stone-canal; the matrix within this would thus have underlain the madre- 

 porite. oes. matrix filling the oesophagus, co.fr. hollow space surrounding 

 the latter and presumed to have been occupied by a circumcesophageal frame 

 of plates (modified flooring-plates). v.r. strands of matrix bridging over 

 the space just mentioned ; they seem to be serially homologous with the podial 

 or pore scars, and may represent water-vessels connecting the adoral podia 

 with a circumoral water-ring. 



Fig. 3. — Interambulacrals showing vermiculate ornament and raised, slightly 

 crenulate suture-margins. From a wax squeeze of a fragment associated with 

 the type, x f . 



Fig. 4. — Flooring-plates in the distal region of the left anterior groove, drawn 



from a wax squeeze of* the external impression, x 6 diam. 

 Fig. 5.— Portion of the anterior groove as seen on the inside of the test, drawn 



from a wax squeeze of the internal cast ; X 5 diam. ia. interambulacrals. 



p. pores for the passage of the podia or of the ampulhe from the podia. 



f.p. flooring-plates. The proximal end is uppermost in the drawing. 

 Fig. 6.— The internal cast of part of a subvective groove ; the complement of 



Fig. 5. x 5 diam. p'. projecting scars of matrix that filled the podial 



pores. 



Fig. 7.— The distal end of the left posterior groove, from a wax squeeze of the 

 external impression ; x 4 diam. Lettering as in Fig. 5. 



Fig. 8. — The central part of the abactinal surface, from a wax squeeze of the 

 external cast (PI. IX), slightly diagrammatised, since details are often obscure 

 in the specimen ; x 3 diam. per. peripheral area. //•. frame, cent, central 

 area, with its flexible plated membrane, raised in five interradially situate 

 lobes. * position of posterior (anal) interradius. p. ia. the meridian in which 

 plates of the posterior interradius (i.e. posterior interambulacrals) pass from 

 the actinal to the abactinal surface and merge with the peripheral plates of 

 the latter. 



[1900 203, 204] 



