94 PEOJF. p. M. Duncan's revision of the 



California, Kerguelen, Philippines, W. coast of Africa, Canaries, 

 Cape de Verd Is., Azores, Mediterranean. 



G-enus Echinocidaeis, gen. nov. (non Desmoidins). Duncan Sf 

 Sladen, 1885, Journ. Linn. Soc. vol. xix. p. 53. Loven, 

 1887, LJch. descr. by LinncBUs, pp. 81 & 95. 



Syn. Arhacia (pars). {Echinus niger, Molina.) 



Test regularly arched, circular in ambital outline, much wider 

 tliau high, gibbous in the interradia at the ambitus. Some radial 

 plates enter the oblique, elongate periproctal ring, and are 

 usually small or as little knobs ; periproctal plates normally four. 



Ambulacra narrow abactinally, and very wide at the peristome ; 

 two rows of plain primary tubercles, separated by miliaries ; 

 plates, when compound, consisting about the ambitus, of four or 

 five components, a large primary plate being adoral, the others all 

 demi-plates, with more or less vertical inner sutures, are aboral. 

 Pairs of pores polyserial at the peristome. 



Interradia with high coronal plates above the ambitus, each 

 with a large tubercle near the poriferous zone, and four smaller 

 which extend towards the median suture, and are near the 

 adoral sutures ; minute secondary tubercles placed above the 

 primaries. Near the peristome the plates are low, and there 

 are many vertical rows of primaries, packed closely and without 

 very definite order. 



Peristome large, interradial ends very small, brancliial cuts 

 broad. One large pit for a single spheridium in each ambulacral 

 median line near the peristome. Spines short on the dorsal 

 part of the test except along the poriferous zones, where they 

 are long. Tentacles heteropodous. Epistroma moderate. 



The union of the vertical median sutures, and also between the 

 ambulacra and interradia, is by dowelling and dovetailing; some 

 plates have lamellae or triangular prominences on their edges and 

 the opposed plate-edges are correspondingly holed. 



Recent. Patagonia and Peru. 



G-enus Ccelopleueus, J._^«ssz2;, 18iO,"(7«i5. Syst. Ectyp. Ech. p. 19. 

 Desor, 1858, Synopsis, p. 96. A. Agassiz, 1874, Revision, 

 p. 267. Duncan Sf Sladen, 1883, Pal. Ind. ser. xiv., Foss. 

 Ech. Kachh and Kattywar, p. 53 ; 1884-85, Sind, Nari series, 

 pp. 251 et seq. ; 1885, Journ. Linn. Soc. vol. xix. p. 27. 



Test moderate in size, tumid and more or less circular in out- 



