170 



POST-TERTL\RY ENTOMOSTRACA. 



with three or four longitudinal rows (more or less interrupted) of blunt rounded spines, 

 and between the rows are a few smaller scattered tubercles of similar character. 

 Length, ^fth of an inch. 



In the recent state this is, perhaps, almost the rarest of the strongly spinous species 

 of Cytliere, which are represented more commonly by C. Dunehnensis, Jonesii, and 

 -antiquata. In those localities where it has been noticed the number of examples 

 found has been extremely small, and the same remark applies to the fossil specimens. 



Distribution. Recent. — Great Britain, Levant, Gulf of St. Lawrence. 



Fossil. — Belfast New Docks. 



39. Cythere antiquata {Baird). Plate XII, figs. 8 — 10. 



1850. Cythereis ANTIQUATA, 5at>J. Brit. Entom., p. 1 76, pi. XX, fig. 2. 

 1868. Cythere antiquata, £rarfy. Monog. Eec. Brit. Ostr., p. 417, pi. xxx, figs. 



17—20. 



Carapace, as seen from the side, rectangular, quadrilateral, about equal in height 

 throughout, length equal to nearly twice the height ; anterior extremity broadly rounded ; 

 posterior rectangularly truncate, both extremities spinous below the middle, the spines of 

 the posterior much longer and stronger than those of the anterior margin ; superior and 

 inferior margins parallel, the latter almost straight, the former cleft into three or four 

 angular segments Avith intervening sulci and forming an angular elevation over the 

 anterior hinge. Seen from below, oblong with projecting lateral alse, which taper 

 towards the front, but terminate abruptly behind, giving to the whole a somewhat 

 arrow-headed outline. From above the outline is more irregular. Surface of the shell 

 more or less tuberculated, bearing two conspicuous longitudinal crests, which terminate 

 abruptly in angular elevations near the posterior extremity of the valves ; these ribs are 

 mostly perforated at the base, the rows of apertures thus produced being very 

 conspicuous on the ventral aspect of the shell. The " eye-tubercle " is very large and 

 prominent. 



Length, -^th of an inch. 



The characters which chiefly distinguish this from the much rarer species C. Whiteii 

 are the more marked rectangular outline, the sharply cut, knife-like, and perforated 

 longitudinal ridges, and the much laciniated or jagged dorsal margin. 



Distribution. Recent. — Great Britain, Ireland, Bay of Biscay, Levant. 



Fossil. — Scotland : Raised beach, Oban. Ireland : Belfast New Docks. 



