350 CRETACEOUS ECHINOIDEA. 



oviductal pore and representing the madreporiform body. Periprocte excentric, elliptical, 

 its minor axis in a line with and near to one of the ambulacral areas. Spines slender, 

 striated. Range of genus, from the Lower Cretaceous to the existing period. Seven 

 British Cretaceous species (pp. 150 — 162). 



Genus 8. — Goniophorus, Agassiz (p. 165). 



Test thin, circular, elevated above, flat below. Ambulacral areas narrow, slightly- 

 undulating, with two rows of secondary alternate imperforate tubercles. Interambulacral 

 areas wide, marked by two rows of primary, alternate, crenulated tubercles. Poriferous 

 zones narrow. Pores simple unigeminal. Oral opening small. Peristome decagonal, 

 slightly incised, and equally lobed. Apical disc large, regularly pentagonal, smooth without 

 incised impressions, ornamented with prominent carinte independent of the form of the 

 ovarial plates. Periprocte excentric, rhomboidal, elliptical, with its minor axis in a line 

 with but distant from one of the ambulacral areas. Disc composed of five ovarial and 

 five ocular plates, and one suranal. Genus confined to Cretaceous strata. One British 

 species (pp. 166 — 169). 



Genus 9. — Salenia, Gray (p. 169). 



Test thin, small, circular, elevated, sides inflated, more or less convex above, flat 

 beneath. Ambulacral areas narrow, gently flexuous, with two or four rows of equal- 

 sized secondary imperforate tubercles. Interambulacral areas wide, with two rows of 

 primary, crenulate, imperforate tubercles. Poriferous zones narrow, pores unigeminal, 

 crowded near the peristome. Oral opening large. Peristome feebly incised, unequally 

 lobed. Apical disc large, shield shaped with deeply undulated border. The ovarial 

 and suranal plates large and pentagonal, the oculars wide and cordate with punctured 

 or incised sutures. Surface of plates smooth, granulated, or striated. Periprocte sub- 

 circular, excentric, and variable in position in the different species, but on the right side of 

 a line passing through the axis of the body. Spines long and slender, aciculate or spatulate, 

 straight or bent. Range of genus, from the Lower Cretaceous strata to the existing 

 period. Nine British Cretaceous species (170 — 186). 



Genus 10. — Cottaldia, Besor (p. 186). 



Test extremely thin, small, circular, inflated, more or less depressed. Ambulacral 

 areas moderately narrow, furnished with numerous small mamillated, imperforate, 

 uucrenulate tubercles, one row to each plate. Ambulacral areas moderately wide, with 

 numerous small equal-sized, imperforate, uncrenulate tubercles, one row to each plate. 

 Poriferous zones straight. Oral opening depressed, large, circular, slightly decagonal, 

 feebly notched. Apical disc solid, narrow, forming a prominent ring composed of five 



