54 CALAMOCRINUS DIOMED.^. 



reticulation becoming gradually more ojjen as we pass towards the centre 

 to the axial canal, is shown in Figures 7 to 9. 



In that part of the stem where there are no flat rings, but only ribbed 

 ones, the radiating ridges and corresponding depressions on the distal and 

 proximal faces correspond to the serrations of the sutures in Plate XXV. 

 Figures 3 and 4. In a ring with a large number of sutural serrations, in 

 Figure 5, the secondary serrations are still more marked, and represented 

 by shorter radiating ridges extending but a little way inward' from the 

 periphery (Fig. 6). The radiating ridges of older joints (Fig. 9) become 

 serrated or undulating disconnected lamellae (Fig. 10). 



In those parts of the stem in which the axial canal occupies a propor- 

 tionally large space of the face of the joint (Plate XXV. Figs. 7, 8), the 

 radiating lamella3 of course do not extend even to the edge of the axial 

 chamber in the joint (Figs. 3, 4, 6), but are lost in the more open reticu- 

 lation of the face of the joint near the outer edge of the axial cord. 



As the axial ring becomes proportionally smaller, the radiating ridges 

 extend nearer the centre of the face of the joint (Plate XXVI. Figs. 5, 6), 

 and at the same time begin to show tiaces of the peculiar arrangement of 

 disconnected radiating ridges (Fig. 4), which becomes more prominent in 

 some of the lower stem joints. In an older joint (Fig. 2) the central 

 reticulation also assumes a radial arrangement, and at the same time 

 disconnected short arcs form part of the general circular lines crossing 

 the radiating lines of the middle third of the face of the joint (Figs. 2, 3). 

 When we come to the lowest joints of the stem, the circular lines of 

 Figure 2 have disappeared, and the radiating lamellae extend to the very 

 edge of the axial cord (Fig. 9). The lamellae of the outer edge of the 

 face which extend to the periphery from the edges of the radiating 

 lamellae (Fig. 10) form a narrow bevelled plane of flat ridges and grooves, 

 which leave an open space between the upper and the lower edge of the 

 sutures (Figs. 1, 11). The reticulation of a part of one of the joints 

 (Fig. 8) resembles in general that of the Hexactinellidae, each node sending 

 off six spokes to form the connecting network. 



The lower face of the basal ring (Plate XIX. Fig. 1) is bevelled, rising 

 from the outer milled edge towards the axial canal, so as to leave quite 

 a cavity between this face of the basals and the upper face of the top 

 stem joint. The lower foce of the anchylosed basal ring is marked by 

 indistinct radiating: ridires extendintj from the milled ed<;;e of the rina; to 



