SUMMARY. 359 



near the margin. Apical disc elongated, composed of four perforated genital and five 

 perforated ocular plates. Genus found in the Cretaceous strata. Seven British 

 Cretaceous species (pp. 293—304, 325—327). 



Genus 28. — Infulaster, Hagenow (p. 305). 



Test thin, narrow, oblong, ovato-cordate. Anterior half very much elevated, rising 

 into a prominent vertex. Anteal furrow narrow, deep, directed obliquely downwards and 

 backwards with angular borders. Plates covered with very small granules, and with a 

 few primary tubercles near vertex, and at sides and centre of under surface. Sur-anal 

 fasciole present. Oral opening transverse near furrow. Anal opening oval, high up on 

 truncated border. Genus found in the Cretaceous strata. Two British Cretaceous 

 species (pp. 305 — 308). 



Genus 29. — Holaster, Agassiz (p. 309). 



Test thin, oval, cordiform, convex above, flat below, covered with granulations and a 

 few tubercles irregularly arranged. Pairs of antero- and postero-lateral ambulacral areas 

 lanceolate, widely apart above, joined below. Poriferous zones with elongated pores in 

 single pairs. Single anterior ambulacrum lodged in a shallow central furrow with 

 minute pores. Ambulacral summit central or subcentral. No fasciole. Oral aperture 

 transversely oval and perfectly bilabiate, near anterior border in a shght depression. 

 Apical disc elongated with four perforated ovarial plates and five perforated oculars. 

 Genital plates disposed in pairs, the anterior being separated from the posterior by a 

 pair of ocular plates. Anal opening oval, low down near base. Range of genus, from 

 Middle Cretaceous to Middle Tertiary. Six British Cretaceous species (pp. 310 — 324). 



• 



Genus 30. — Echinocgrys, Breynius (p. 327). 



Test thin, more or less oval, elevated, helmet shaped, convex or conoidal above, flat 

 below. Ambulacral areas identical, radiating from summit. Pores round, in single 

 pairs, set obliquely apart in the middle of the ambulacral plates and forming two rows 

 in each area. Oral opening transversely oval, bilabiate near border. Apical disc 

 elongated, formed of four ovarial and five ocular plates. The two pairs of ovarial plates 

 separated by a pair of oculars. Anal opening small, oval in vertical direction, marginal 

 or infra-marginal. Genus found in Upper Cretaceous strata. One British Cretaceous 

 species (pp. 328 — 334). 



