KRITHE. XESTOLEBERIS. 41 



2. Krithe glacialis, Brady, CrossJiey, ^ Robertson. 



Keithe glacialis, Brady, Crossket/, Sf Robertson. Monogr. Post-Tertiary Entom., 

 Pal. Soc, 187J., p. 184, pi. vi, figs. 21—24 ; Jones & Sher- 

 born, Geol. Mag., 1887, p. 456, pi. xi, figs. 15 a, h. 



A sraootli specimen of Krithe from tlie London Clay of Piccadilly is so 

 extremely close in every feature to K. glacinlis from Scotland and Norway, except 

 in tlie apparent papillge of the latter, that we cannot separate it from this 

 later form. 



Collected by Messrs. Sherborn and Chapman. (British Museum.) 



3. Keithe Londinensis, Jones 8f Sherborn. Plate II, figs. 20 a, b. 



Keithe Londinensis, Jones ^ Sherborn. Geol. Mag., 1887, p. 456, pi. xi, figs. 



14 a, b. 



Carapace narrow-obovate, not quite semicircular in front, subacute posteriorly. 

 In edge-view the anterior third is compressed and wedge-shaped, the middle is 

 swollen, and the posterior third is compressed, and ends in the usual notch formed 

 by the produced ends of the two valves. Surface smooth and shining. In this 

 last feature it resembles other forms of this genus, but in its outlines it differs 

 from any we know. 



From the London Clay of Piccadilly. Collected by Messrs. Sherborn and 

 Chapman. (British Museum.) 



Bornemann's Bairdia pernoides (' Zeitschr. d. g. Ges.,' vol. vii, 1855, p. 358, 

 pi. 20, fig. 7) is a somewhat similar Krithe of the same geological age. 



XV. XESTOLEBERIS, G. 0. Sars, 1865. 



1. Xestoleberis Colwellensis, Jones 8f Sherborn. Plate I, figs. 13 b, c. 



Xestolebehis Colwellensis, Jones Sf Sherborn. Geol. Mag., 1887, p. 456. 



Carapace ovate in outline, and subovate in edge-view, with spinulose surface. 

 This is near X. aurantia (Baird), but blunter anteriorly. 

 Erom the Tertiary of Colwell Bay. (British Museum.) 



