OP THE TEST OF THE TEMITOPLETJEID^. 357 



are pits in relation to the angles of plate ; c are the semi-pits. Mag- 

 nified. 



Fig. 3. The edge of an inteiTadial plate along the vertical or median series of 

 sutures, a and b are the parts of the pits pertaining to the plate, the 

 rest being in the adjoining interradial. o is the semi-pit. The great 

 development of the pits below the surface is seen ; and they are sepa- 

 rated by projections of the plate's edge, broad above, narrow below. 

 These projections carry the sockets and knobs of the suture. Below g 

 there is a long socket followed by three pits ; and below the large 

 tubercle a long projection is seen, and below it more knobs. Beneath 

 the expansion of the pits, on the reticulate tissue of the test, are soma 

 knobs and sockets. Magnified. 



Kg. 4. Theactinal edge of the same plate. A series of knobs projects. Mag- 

 nified. 



Fig. 5. The aboral edge of an interradial plate, showing three or more irregular 

 rows of sockets. Magnified. 



Fig. 6. View along the line of suture of the ambulacral tentaculiferous plate 

 and the interradial plate ; the edge of the ambulacral plates is drawn. 

 The deep and narrow pits (in section), some expanding, are shown ; 

 and between them are numerous knobs. These fit into the sockets in 

 the interradial plate (fig. 7). Magnified. 



Fig. 7. An interradial plate, ambulacral edge : the portions of pits correspond 

 with others on the ambulacral edge, the raised lines between the pita 

 carry sockets. Magnified. 



Fig. 8. View of the edge of a median ambulacral plate along the line of vertical 

 suture. The pits are large, and they extend on the edge of the plates 

 They are separated by ridges, some knobbed and others with sockets. 

 A process arises on the floor of the pit which is sutural. Mag- 

 nified. 



Fig. 9. An ambulacral series from within the test. The tentaculiferous pores 

 are seen, and on the edge a number of minute knobs. Magnified. 



Fig. 10. Abactinal edge of a coronal plate of Temnopleurus toretcmaticus, show- 

 ing sockets, some in linear series. Magnified. 



Fig. 11. An actinal edge of an interradial plate near the apical system, showing 

 knobs. Magnified. 



Fig. 12. The median interradial suture and pits. Magnified. 



Fig. 13. The suture and pits of the interradial plates adjoining an ambulacral 

 area : sockets and pits. Magnified. 



25* 



