32 PEOF. p. M. Duncan's eeviston op the 



YI. DiTisiON. Syn. Subgenus Fhyllacanthus, Brandt, 1834, 

 Eec. d. Aetes de I'Acad. Imp. d. Sci. de St. Petersb., pub. 

 1835, Additions, p. 267 ; A, Agassiz, Eevision, 1873, p. 387. 



Test large, swollen, comparatively tbin, and witb tbe maximum 

 of coronal plates, 8-11. Apical system large ; the basal plates 

 in contact, or separated by radial and anal plates. Ambulacra 

 almost straight or very sligbtly undulating, broad ; the pores in 

 a broad zone, and united by a groove. Primary tubercles 

 o£ tbe interradia large, perforate, non-crenulated, scrobicular 

 circle large, areola sunken, mamelon small. Miliary area wide. 

 Spines mostly solid, the primaries varying greatly in shape 

 and size, cylindrical, triangular, flattened in section, elongate 

 or club-shaped, blunt or pointed ; flutiugs strong, either as 

 simple striation, or as continuous or broken lamellae variously 

 projecting, sometimes forming secondary spinules. — (P. dulia, 

 Brandt. See Lov^n's remarks upon the subgenus in ' Echin. 

 described by Linnaeus,' 1887, p. 148.) 



VII. Division. Syn. Grenus Porocidaris, Desor, Synopsis, 

 pp. 46, 47. Wy. Thomson, 1874, Phil. Trans, p. 726. 

 Ambulacra broad and straight ; pores wide apart, united by a 

 groove. Primary interradial tubercles with small perforate and 

 crenulated mamelons ; the scrobicules more or less transversely 

 oval, with shallow grooves more or less defined, radiating from 

 the pej'iphery towards the centre, along the flank of the 

 tubercles, with or without pores or depressions at the outer 

 extremity of the grooves. Some spines flattened, with strongly 

 serrated edges, resembling tbe smaller peristomial spines of 

 Cidaris 'paj^illata. — {Cidaris purpurata, Wyv. Thoms., the type.) 



Subgenus Goniocidaeis (genus), Desor, 1846, Agassiz Sf Desor, 



Cat. Mais. d'Ech., Ann. d. Sci. Nat. vol. vi. p. 337. LutTcen, 



1864, Ved. Med. f. Nat. Kjolenli. p. 137. A. Agassiz, 1873, 



Hevision, p. 395. 



Test high ; coronal plates numerous ; ambulacra narrow ; the 



median sutural regions of interradia and ambulacra sunken, 



forming with the horizontal sutures a zigzag, culminating in 



pit-like depressions at the angles of junction of the sutures. 



