26 



T. H. Withers — Girripedesfrom the Chalk. 



along the inner oceludent margin, marked with very oblique lines, and a considerable 

 part of the apex, marked with transverse lines, probably indicating the extent to- 

 ■which the valve projected freely. 



Comparison tvith other Species. These terga are quite unlike any 

 valves either of Pollicipes or Scalpelhim with which I am acquainted. 

 The terga which apparently come nearest to them are those of 

 Scalpellum maximum (J", de C. Sowerby) and its varieties. These, 

 however, differ much from S. longissimum, especially in the more 

 pointed and produced basal angle, the pointed apex which is curved 

 towards the carina, and in the general shape of the valves, which are 

 much more curved, and in some specimens almost crescentic. 



Pollicipes filosus, sp. nov. Fig. 6. 



Diagnosis. Carina almost straight, transversely rounded, basal 

 margin obtusely V-shaped, with basi-lateral angles somewhat produced, 

 and the whole exterior surface ornamented with fine rounded longi- 

 tudinal ridges. 



Material. Two carinaa. The smaller specimen is not quite 

 complete, but the portion preserved measures 9 "3 mm. in length and 

 2-3 mm. in greatest width. The largest specimen is complete, but 

 somewhat crushed, so that it is impossible to give its accurate breadth. 

 It is 22-6 mm. long, and measured about 5 or 6 mm. in breadth. 



Holotype. The larger and complete carina (Fig. 6). 



6b. 

 6c. 



Qd. 



Fig. 6a. Pollicipes Jiloms, Withers, sp. nov. External view of carina, x 2 diarn. 

 Upper Senonian, Belemnitella mucronat a -zone : Eedlynch, near Salisbury,. 

 Wilts. 

 Id. Side view. 



Id. Transverse section at one-third from apex. 

 Id. Transverse section at one-third from base. 

 ,, 6e. Id. Enlarged view of external surface near base, showing direction of 

 growth-lines, and the increased number of longitudinal ridges near its inner 

 margin, x 4 diam. 



Horizon and Locality. Upper Senonian, Belemnitella mucronata- 

 zone : Clarendon and Eedlynch, near Salisbury, Wilts. 



Description of Holotype. Carina almost straight, long, narrow, widening very 

 gradually from the apex, extremely convex transversely, obscurely carinate, inner 

 margin straight ; apex sharply pointed ; basal margin obtusely V -shaped, with basi- 

 lateral angles produced into spur-like processes ; parietes narrow and slightly 

 inflected. Valve extremely thin near its base, gradually becoming thicker towards- 



