ISO 
OOLITIC ECHINODERMATA. 
the apex, two meeting at the summit, and three nearer the anal opening. Poriferous 
zones narrow, continuous ; pores unigeminal. Interambulacral areas covered with small 
perforated and crenulated tubercles. Oral opening small, obtusely pentagonal, excentric. 
Jaws absent. Anal opening small, oval in the middle of non-sulcated margin. Genus found 
in the Oolitic and Cretaceous strata. Three British Oolitic species (Vol. I, 309 — 318). 
Family VIIL— ECITINOBRISSID^, Wright (Vol. I, p. 830). 
Test thin, oblong, subpentagonal, circular, covered uniformly with small uncrenu- 
lated imperforate tubercles, largest on the under side. Ambulacral areas narrow and 
petaloid, lanceolate above, expanded in the middle, contracted and open below. Pori- 
ferous zones at the border and base narrow ; pores small, equal. Interambulacra wide. 
Apical disc small. Oral opening small, subcentral, and pentagonal, sometimes lobed. 
Jaws absent. Anal opening large, placed in a furrow on the upper surface or at the 
margin. The Echinobrissidge range from the Oolitic to the existing period. Two 
British Oolitic genera (Echinobrissus and Clypeus), and sixteen species. 
Genus 19. — Echinobrissus, Breynius (Vol. I, p. 331). 
Test thin, small, oval or subcircular, convex above, subconcave below, rounded in 
front, truncated, and generally widest behind ; marked by small tubercles, which are 
larger on the under surface than on the upper. Ambulacral areas petaloid on upper 
surface, straight on lower. Oral opening small, excentric. Peristome pentagonal or 
oblique. Jaws absent. Anal opening circular, on upper surface, in a sulcus sometimes 
extending the whole distance, sometimes only a part, from the apical disc to the border 
of under side. Apical disc small, square, compact. Genus ranges from the Oolitic to 
the existing period. Eight British Oolitic species (Vol. I, pp. 333 — 353). 
Genus 20. — Clypeus, Klein (Vol. I, p. 360). 
Test large, discoidal ; upper surface moderately subconvex, depressed ; under surface 
flat, concave, undulated. Ambulacra petaloid on upper surface, straight on under surface. 
Oral opening central or subcentral, small, lodged in a depression. Peristome lobed. 
Jaws absent. Anal opening oval or pyriform, situated in a sulcus extending wholly or 
partially from the apical disc to the lower border. The genera is found in the Oolitic 
strata. Eight British Oolitic species (Vol. I, pp. 361—382, 466). 
