268 Proceedings of the Royal Irish Academy. 



Genua X. OiCPHALOPELTA, Ehr. 



Yalres as in Actmoptycliiis, but having a marginal spine in each, 

 compartment. 



Omplialopelta areolata, (Ehr.) ITarine. 



Valve having six compartments, areolate ; suhmarginal spines small. 



Ehr. Mic, T. sxxv., A. Ealfs, in Pritch., p. 841, PL viii., fig. 

 15.— Actinocyclus areolatus, BrightTvcU. Q. J. 11. S., 1860, p. 93, PL 

 v., fig. 1. 



Arran Islands, Co. Gal^ay. 



Genus XI. AcTccocxcLrs, Ehr. 



"Disk minutely and densely punctated, or cellulose, generally 

 divided by radiating single or double dotted lines, and having a small 

 circidar hyaline intramarginal pseudo-nodule." " The disk is not 

 undulated." Ealfs. To this description may be added, that the 

 species of this genus usually exhibit a border in -which the strias are 

 unlike those of the remainder of the disk ; the stride also almost or 

 altogether reach the centre. 



Adinocychis Ralfsii, (AVm. Sm.) llarinc. 



Yalve highly in'idesccnt under a low power. Strife radiate, monili- 

 form ; puncta nearly of unifonn 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 wdde, minutely 

 punctate ; submarginal nodule lai'ge, round ; no central nodule, but 

 the central portion marked by a few scattered puncta ; diameter about 

 •0042. (PL 27, fig. 1.) 



Ealfs, in Pritch., p. 835, PL v., fig. 84. — Eupodiscus Ealfsii, "Wm. 

 Sm., B.D., Yol.ii., p. 86. 



Lough Eay, Co. Kerry. Stomachs of Pectens, Dalkey Sound, Co. 

 Dublin. Stomachs of Ascidians, Belfast Lough, Co. Antrim. 



Actinocyclus moniliformis, (Ealfs.) Marine. 



Strice moniliform, principal rays about twelve in number, running 

 radiately from centre to border ; intermediate rays becoming gi'adually 

 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, margiaal. Diameter about -0034. (PL 

 27, fig. 2.) 



