176 
OOLITIC ECHINODERMATA. 
Getius 10. — Magnotia, Michelin (Vol. I, p. 190). 
Test thin, small, inflated, with a concave base. Ambulacra! areas narrow 
and straight. Interambulacral areas marked by a deep median depression, and bearing 
many small, equal-sized, imperforate, and uncrenulated tubercles. Poriferous zones 
narrow ; pores unigeminal. Genus found in the Oolitic strata. One British Oolitic 
species (Vol. I, p. 191). 
Genus 11. — Polycyphus, Agassiz (Vol. I, p. 196). 
Test thin, small, hemispherical. Ambulacral areas narrow and straight. Interambu- 
lacral areas wide, with a slight median depression. Both the ambulacral and the inter- 
ambulacral areas are covered with numerous small equal-sized, regularly-arranged, imper- 
forate tubercles, which are much larger on the under side than on the upper surface, 
t'oriferous zones wide and depressed. Pores in triple oblique pairs, which become most 
numerous near the peristome. Oral opening wide. Peristome pentagonal, slightly 
notched, and marked by unequal lobes. Genus found in the OoKtic strata. Two 
British Oolitic species (Vol. 1, pp. 197—199). 
Genus 12. — Stomechinus, Besor (Vol. I, p. 203). 
Test thin, of moderate size, globular, conoidal, more or less depressed. Ambulacral 
areas narrow^ one third the width of the ambulacral, bearing two marginal rows of 
numerous small tubercles, and sometimes two additional rows of a smaller size. Inter- 
ambulacral areas wdde, bearing two rows of larger tubercles and several rows of smaller 
tubercles. Miliary zones sometimes broad and granular, sometimes narrow and naked. 
Poriferous zones moderately wide ; pores arranged in triple oblique rows. Mouth 
opening large. Peristome subpentagonal, deeply notched, and unequally lobed. Spines 
short, stout, and bluntly pointed. Genus found in the Oolitic strata. Six British Oolitic 
species (Vol. 1, pp. 204—217). 
Family V.— SALENIADtE, WHgU (Vol. I, p. 226). 
Test thin, small, spheroidal or depressed. Ambulacral areas always narrow, straight, 
or flexuous, with two rows of small tubercles, which alternate with each other on the 
margins of the areas. Interambulacral areas Avide, with two rows of large primary 
tubercles, perforated or imperforated, with bosses having crenulated summits. Poriferous 
zones narrow ; pores unigeminal, except near the peristome, where they are obliquely 
