152 PEor. P. M. Duncan's eevision op the 



tumid iiiterporiferous ai eas. Beyond the petals aud actinally, tlie 

 pores are Biiinerous and are oblique. 



Small pores iu great numbers in oblique transverse lines in the 

 plates, to the periston. e ; aetinal grooves straight, more or less 

 developed, perlorattd. The second amhulacral plates from the 

 perifctome krge and uniting aiouud, so as to iiatrude upon the 

 interradia. 



Interradia narrow between the petals, the double apical plates 

 may have a genital pore in their median sutures; a single plate 

 at the peristomial "margin ; discontinuous actinally. Pores 

 perforating the plates slightly abactiually aud considerably 

 actinally. 



Peristome sunken, polygonal, thin-edged, with ten amhulacral 

 and five iuterradial plates ; buccal poj es at the edge ; two 

 spheridia hidden in each ambulacrum. Periguathic girdle dis- 

 continuous, placed beneath the jaws ; the processes tall, narrow, 

 close, in pairs, arising from the edges of amhulacral plates. Jaw s 

 large ; pyramids unequal, expandt d dorsally ; teeth in more or less 

 vertical grooves placed on their inner surface ; depressions 

 below the pyramids for the articulation of the perignathic 

 processes. Periproct infra-marginal, near or at the edge, pos- 

 teriorly. 



"Within, numerous concentric partitions near the edge of the 

 test, forming false walls, composed of fused or perfect needle- 

 shaped or stout pillars expanding at the roof and floor ; around 

 the distal part of the petals and reaching to the floor are needles 

 and supports expanding above and below, shutting ofi", incom- 

 pletely, the amhulacral from the intestinal areas ; this structure 

 may extend some distance between the petals. The amhulacral 

 plates with projecting ridges or needles, not coalescing to cover 

 over the v,ater-system or to form a double wall. 



Tentacles of the petaloid part of the poriferous zones branchial 

 and pectinated in whorls ; the tentacles of the small pores 

 prehensile, with a calcareous support to the disk. Pedicellarise, 

 some large stout-headed and narrow-ended tridactyles upon short 

 calcareous stems ; other pedicellarise long, with narrow valves, or 

 gemmiform and upon longer stems. Tubercles small, largest 

 actinally, in sunken scrobicules, the intermediate structure with 

 miliaries ; amhulacral ornamentation smallest. 



Spines very short for the size of the test, fine, cylindrical, 

 largest and sometimes spathiform actinally. 



