44 THE ENTOMOSTRACA OF 



C. papillosa, Bosquet, on the other ; and there are several allied forms figured by Reuss 

 (Haidinger's Abhandl., iii, pi. 8), but they do not appear to be specifically identical. 

 The species also figured and described by M. Bosquet as Bairdia punctatella (Descript. 

 Entom. Tert. p. 75, tab. 1, fig. 10) is not unlike C. pinguis, although smaller; and, 

 like several other species figured on the same plate, is decidedly not a Bairdia. 



No. 4. C^theridea Sorbyana, spec. iiov. Plate IV, figs. 6 a — 6 e. 



INCH. 



Length, ^3 Pleistocene: Bridlington. 



Carapace irregularly triangular and approaching a pentagonal form, — of which 

 the ventral border makes a long straight side, the dorsal two shorter straight sides, 

 oblique to each other and to the remaining sides, whilst lastly the anterior and posterior 

 extremities complete the pentagon, — the former with an obliquely rounded, and the 

 latter with an oblique straight border ; the junction of the ventral and posterior borders 

 forms an angle very slightly rounded ; the anterior border is strongly spined : surface 

 of the valves marked towards the margins with concentric ridges, following the outline 

 of the valve, and connected by short oblique ridges or wrinkles, which are continued 

 over the middle of the valve, where the long ridges become nearly obsolete, forming 

 with the others a strong angular reticulation, sometimes closing up and becoming 

 granular in the centre of the surface ; the long ridges are marked at short 

 regular intervals with trumpet-shaped perforations 1 (fig. 6e). Lucid spots four in 

 one row (System c). 



Dorsal aspect lanceolate ; anterior, acute-oval. 



Found by Mr. H. C. Sorby, f.g.s. (to whom, as an ardent and distinguished 

 geologist, I have much pleasure in dedicating'this peculiar species), in the Pleistocene 

 deposit known as the Bridlington Crag, at Bridlington, Yorkshire. 



No. 5. Cytheridea perforata, Roemer, sp. Plate IV, figs. 14 a — 14e. 



Cytherina perforata, Roemer. Neues Jahrb. f. Min., &c, 1838, p. 516, t. 6, fig. 11. 

 Cythere Hilseana, 2 Jones (non Roemer). Monog. Entom. Cret., p. 10, t. 1, fig. 1. 



1 Seen under the microscope by reflected light, these perforations, being visible in the translucent 

 substance of the valve, appear on that side of the convex valve which is away from the direct rays of light 

 like out-standing blunt spines. This phenomenon occurs also in the punctated and perforated valves of 

 other species, when their substance is translucent 



2 M. Bosquet, having had the opportunity of examining both Roemer's C. Hilseana and my specimens 

 which I referred to that species, has determined that they belong to distinct species. 



