268 Proceedings of the Royal Irish Academy. 
Genus X. OmpHatoprtta, Ehr. ss 
Valves as in Actinoptychus, but haying a marginal spine in each 
compartment. 
Omphalopelta areolata, (Ehr.) Marine. 
Valve having six compartments, areolate ; submarginal spines small. 
hr. Mic., W-xxxv.; A: Ralig” im Priteh p> san ER yen,, a 
15.—Actinocyclus areolatus, Biightwell. Q.J.M.8., 1860, p. 93, Pl. 
Wey ee 1: 
Arran Islands, Co. Galway. 
Genus XI. - Acrrnocyctvus, Ehr. 
‘Disk minutely and densely punctated, or cellulose, generally 
divided by radiating single or double dotted lines, and haying a small 
circular hyaline intramarginal pseudo-nodule.”’ ‘The disk is not 
undulated.’”’ Ralfs. To this description may be added, that the 
species of this genus usually exhibit a border in which the strie are 
unlike those of the remainder of the disk; the strie also almost or 
altogether reach the centre. 
Actinocyclus Ralfsii, (Wm. Sm.) Marine. 
Valve highly irridescent under a low power. Striew radiate, monili- 
form ; puncta nearly of uniform size throughout, the dividing radii equi- 
distant, nearly reaching the centre; the next lines of puncta consider- 
ably shorter than the radii; the next again still shorter, exhibiting 
numerous subulate blank spaces; border tolerably wide, minutely 
punctate; submarginal nodule large, round; no central nodule, but 
the central portion marked by a few scattered puncta; diameter about 
"0042. (PI. 27, fig. 1.) 
Ralfs, in Pritch., p. 835, Pl. v., fig. 84.—Eupodiscus Ralfsii, Wm. 
Sm., B.D., Vol. 1., p. 86. 
Lough Kay, Co. Kerry. Stomachs of Pectens, Dalkey Sound, Co. 
Dublin. Stomachs of Ascidians, Belfast Lough, Co. Antrim. 
Actinocyelus moniliformis, (Ralfs.) Marine. 
Strie moniliform, principal rays about twelve in number, running 
radiately from centre to border; intermediate rays becoming gradually 
shorter and parallel, except near the border, where a few short ones 
meet them at an angle. About four puncta, closely approximated in 
the centre, present the appearance of a nodule; border narrow, punc- 
tate; pseudo-nodule small, marginal. Diameter about ‘0034. (PI. 
27, fig. 2.) . 
