CYTHERE. 159 



the surface is also characteristic. It seems to be a rare species in the recent state, having 

 been noticed very sparingly only on the west of Scotland, in the Channel Islands, and 

 Spitzbergen. 



Distribution. Recent. — Great Britain, Spitzbergen. 



Fossil. — Scotland : Raised beach, Oban. 



25. Cythere macropora, Bosquet. Plate XIV, figs 1 — 3. 



1852. Cythere mackopoka. Bosquet. Entom. foss. terr. tertiair., p. 97, pi. v, 



fig. 2. 

 1856. — — Jones. Monog. Tert, Entom., p. 35, pi. iii, figs. 



9 a— 9 e. 



Carapace, as seen from the side, oblong, quadrangular, greatest height situated near the 

 front and equal to more than half the length ; anterior extremity somewhat obliquely 

 rounded, and serrated below the middle ; posterior subtruncate, its lower half somewhat 

 produced and divided into five or six broad teeth ; superior margin sloping nearly in a 

 right line from before backwards ; inferior nearly straight. Seen from above, the outline 

 is oblong, subhexagonal, with irregularly parallel sides and broadly mucronate extremities, 

 constricted in the middle. The surface of the shell is covered with deep, closely set 

 angular pits, each valve bearing a large rounded central tubercle, and a strongly marked, 

 rounded, encircling ridge just within the anterior, inferior and posterior margins ; the 

 central surface of each valve has on each side of the very prominent and largely 

 developed contact-margins a single longitudinal series of large angular fossas; 

 the posterior portion of the contact-margins is ornamented in a similar manner. 

 Length, ^th of an inch. 



A handsome and very well characterised species, of which a few specimens only 

 have occurred, from Hopton Cliff, Great Yarmouth. Professor Rupert Jones's measure- 

 ment is double that given by M. Bosquet, with the latter of which ours closely 

 agrees. 



Distribution. Fossil. — England: Post-tertiary, Hopton Cliff; Pliocene, Suffolk. 

 France : Middle Eocene. 



