OF THE ANTWEEP CRAG. 397 



slightly rounded ; dorsal margin forming a continuous curve from its highest point to 

 the infero-posterior angle ; ventral margin almost straight. Seen from above the out- 

 line is ovate, widest in the middle, and tapering evenly to the extremities, which are 

 rather obtuse ; width nearly equal to the height. End view nearly circular. Surface 

 of the shell perfectly smooth. Length 3^ inch (0-85 millim.). 



This differs from the typical form of the species only in being entirely destitute of 

 papillose sculpture. The papillose form (which, however, varies very much in its 

 surface ornament) has been found in the fossil state in most of the Post-tertiary beds 

 of Scotland, as well as in Norway and Canada, and by M. Bosquet in many of the 

 Tertiary beds of France. In the living state it occurs plentifully in the seas off 

 Norway and Great Britain and Spitzbergen, as well as in Baffin's Bay and the Gulf of 

 St. Lawrence. My memoranda of the particular bed or beds in which this form 

 occurred have unfortunately been lost. 



Cytheridea pinguis, Jones. (Plate LXII. figs. 3 «-3 d.) 

 Cytheridea pinffuis, Jones, Tertiary Entomostraca of England, p. 43, pi. ii. figs. 4a-4h. 

 ? Cytheridea fabceformis, Speyer, op. cit. p. 52, pi. ii. fig. 1. 



Carapace, as seen from the side, ovato-triangular, highest a little in front of the 

 middle ; height equal to more than half the length ; extremities rounded, dorsal 

 margin very boldly arched, almost gibbous ; ventral slightly convex ; seen from above 

 the outline is ovate, scarcely at all tapering to the extremities, which are rather broadly 

 rounded ; the width is nearly the same throughout, and is equal to half the length. 

 End view nearly circular. The shell-surface is nearly smooth, but is usually covered 

 with closely-set small punctures. Length -^f inch (0"9 millim.). 



Professor Jones's specimens were found in the Pliocene of Suffolk. Those described 

 in this memoir are from all the Antwerp beds except only that of the " Sables a Bryo- 

 zoaires." It is one of the more abundant species. 



Cytheridea cypridioides, nov. sp. (Plate LXIX. figs. 6 a-6 e.) 

 Carapace tumid, ovate : seen from the side the outline forms about two thirds of a 

 circle, the dorsal margin being excessively arched, and the ventral slightly convex ; the 

 extremities are rounded, the posterior much the narrower and rather flattened; greatest 

 height equal to two thirds of the length. Outline seen from above regular ovate, extre- 

 mities obtuse ; width equal to more than half the length. Surface of the shell perfectly 

 smooth. Length -^ inch (0'85 millim.). 



A few specimens of this species were found in the " Sables moyens " (zone a Bryo- 

 zoaires). I am by no means sure that the form called in this memoir C. pa^nUosa, var. 

 IcBvis, may not be merely the male of this species. 



Cytheridea mulleri (Miinster). (Plate LXII. figs. 4 a-4 e.) 

 Cythere mulleri, Miinster, Jahrb. fiir Mineralogie, 1830', p. 62, and Neues Jahrb. 1835, p. 4J6 

 (fide Jones and Bosquet) . 



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