GKNEEA AND aEOUPS OP THE EUHINOIDEA. 145 



slightly convex abactinallj, concave actiually near the central 

 peristome. 



Apical system central ; sutures fused ; madreporite central, 

 with only one large pore ; four genital pores ; radial pores 

 variable in size. 



Ambulacra broader than the interradia, short where slightly 

 petaloid, widely open distally; pairs of pores few and increasingly 

 far apart ; the horizontal sutures beyond the petaloid part, 

 pierced by pores, some pores in the plates near the peristome. 



Interradia narrow, continuous, a single broad plate in each, at 

 the peristome and also at the apical end. 



Peristome central, pentagonal. Perignathic ridges tall, broad, 

 one on each peristomial interradial plate. Jaws small ; pyramids 

 rather high, flat ; teeth superior, inclined. Periproct between 

 the peristome and the posterior edge of the test ; anal plates 

 four or five, triangular. Ornamentation of uniform small perforate 

 tubercles, carried over the apical system. Spines short and 

 slender. Within the test are five pairs of partitions limiting the 

 ambulacra, for a short distance. A single spheridium in each 

 ambulacrum, covered. 



Fossil. Cretaceous to Miocene : Europe. Pliocene : England 

 and Europe. Nummulitic : Asia and Africa. 



'Recent. N. Atlantic and British Seas, Norway, Azores, Jose- 

 phine Bank, Mediterranean, Elorida, Caribbean Sea. Littoral to 

 105 fathoms. 



Subgeiius Scutellina., (genus) Agassiz, 1841, Monogr. d'Ech. 

 viv. etfoss. livr. 2, Les Scutelles, p. 98. 



Test small, circular in outline. Jaws broad, low ; pyramids 

 horizontal; teeth superior. Periproct small, variable, marginal, 

 or more or less supra- or iuframarginal. 



Fossil. Tertiary : Europe. 



Genus Sismondia, Desor, 1858, Synopsis, p. 225. {Enlarged.) 

 Test of small or medium size, subpentagonal or ovoid, depressed, 



inflated at the margin. 



Apical system central or subcentral, flush ; only a single pore 



of the madreporite is present ; four basal plates and their pores 



are large ; radial plates small, pores minute. 



Ambulacra, petaloid parts usually long, more or less open ; 



pairs of pores few, not continued actinally ; a great number of 



LINN. JOUEN.- — ZOOLOGY, YOL. XXIII. 10 



