GENERA. AND GROUPS OP THE ECHINOTDEA. 



263 



Lateral interradia with large plates nest to the very small 

 peristomial ones ; plates 2 and 3 of zone " a " of the right pos- 

 terior interradium united. Posterior labrura elongate ; sternum 

 symmetrical and small. 



Peristome semilunar, open, the margin nearly formed by am- 

 bulacral plates, the interradial plates just entering or not, except 

 the posterior, which forms a labrura. Periproct in the posterior 

 truncation, in a depression, ovoid. Tubercles small upon the 

 actinal surface and on the margin. Several large perforate 

 scrobiculate sunken primary tubercles, their mamelon small and 

 doubtfully crenulate, in all the interradia, except the posterior, 

 dorsally. 



An internal fasciole closed; a subanal, broad, closed, envir(m- 

 ing six of the ambulacral pores on either side beyond the fifth 

 plates ; a peripetalous fasciole passing beyond the petaloid parts 

 of the ambulacra and limiting the great tubercles. 



The spines of the large tubercles, none of which are on the 

 posterior interradium dorsally, are long, slender, curved; the 

 actinal spines very small and slender. 



Fossil. Miocene : E. India ; Europe ? 



Mecent. Eed Sea, Japan, Sandwich Islands, Australia. 



The species said to be Eocene by d'Archiac and Haime are 

 now known to be Miocene, and the species described by 

 M. Cotteau from the Antilles are not members of the genus 

 according to Desor. 



Genus Lovekia, Agassiz Sf Desor, 1847, Catal. Mais., Ann. d. 

 Sci. Nat. vol. viii. p. 10. Gray, 1855, Cat. Bee. Ech. Brit. 

 Mus. pt. i. p. 44. A. Agassiz, 1872-74, Bevision, pp. 139, 

 574. Loven, 1874, Etudes, pi. xliii. Duncan, 1877, Quart. 

 Journ. Geol. Sac. vol. xxxiii p. 58, pi. iv. figs. 5-8. McCoy, 

 1879, Pal. Vict. Geol. Surv. decad. vi. p. 37. 

 Syn. Sarsella, Pomel ; Tuleraster, Peron ? 

 Test moderate or rather small in size, variable in thickness, 

 thin or rather stout, cordiform or ovoid, depressed or rather 

 tumid in the thick forms ; an anterior groove and a posterior 

 truncation. 



Apical system escentric in front, with four perforated basals, 

 and the madreporite separating the posterior basals and radial 

 plates. 



