238 ECHINODERMATA—ECHINOIDEA SUB-BRANCH III 
more rarely cuts; one in the median line of the posterior dmb, the others 

Fic. 383. 
Scutella suwbrotundata, Lam. Miocene; Bordeaux. A, B, Ventral and dorsal aspects. C, Section, 1/}. 
in the dmb. Amb petaloid dorsally, the posterior pair the longest. Pliocene 
and Recent. 
Lenita, Desor. Eocene. Jotula, Klein. Recent. Arachnoides, Breyn. 
(Asterodaspis, Conrad). Pliocene and Recent. 
Order 5. SPATANGOIDA. Duncan. 
“ Buechinoidea with an actinal or a frontal peristome, and a periproct situated 
beyond the dorso-central system, in the posterior interambulacrum , without external 
branchiae » jaws, teeth, and perignathic girdle. Spheridia numerous.’—Dunean. 
Sub-Order A. CASSIDULOIDEA. Duncan. 
Ambulacra abactinally simple, petaloid or sub-petaloid, usually similar. Some 
or all of the interambulacra with a single peristomial plate , the postero-lateral areas 
symmetrical actinally, without any fusion of plates; no plastrons.  Peristome 
variously shaped, with or without floscelles, 
Family 1. Hchinoneidae. Wright. 
Test tall, or low and tumid dorsally ; tumid and rarely flat actinally. Apical 
system central, compact, with four perforated basals. Ambulacra similar, dorsally 
apetalous or sub-petaloid. Pores in simple pairs or in oblique triplets actinally ; no 
floscelle. Peristome oblique or transversely elliptical, rarely symmetrical. Periproct 
actinal, marginal or supra-marginal. Cretaceous to Recent. 
