T. H. Withers — Cirripedes from the Chalk. 



23 



one right tergum. Three of the carinae are very small and measure 

 only ahout 2 mm. in length, the fourth measures 8 mm., and the fifth 

 (Fig. 3), although slightly broken at each extremity, measures 12-6 mm. 

 in length. The right tergum is slightly broken at the apex and basal 

 angle, the portion remaining measuring 9'5 mm. in length and 3'6 mm. 

 at its widest part. 



Distribution. — Upper Senonian : Actinocamax quadratus- zone, East 

 Harnham, near Salisbury ; Belemniiella mucronata- zone, Alderbury 

 and Clarendon, near Salisbury, "Wilts ; Actinocamax qtiadratus-zone, 

 Reims, France ; Belemnitella-mucronata-zone, Isle of tliigen. Upper 

 Senonian and Maestri chtian: St. Pierre, Duchy of Limbourg, Holland. 

 Upper Senonian : Frere, near Tongres. Maestrichtian : Sichen, 

 Belgium. 



Fie. 3«. 



Si. 



3c. 

 3d. 



ib. 



Scalpellum Darivinianum, J. Bosquet, x 4 diam. External view of 

 carina, with umbo in sub-central position. Upper Senonian, Belemniiella 

 mucronata-zone : Alderbury, near Salisbury, "Wilts. 



Id. Side view. 



Id. ' Transverse section at one-tbird from apex. 



Id. Transverse section at one-tbird from base. 



Id. External view of right tergum. x 4 diam. 



Id. Inner surface of same showing- series of tubercles. 



Description of Carina. Carina (Fig. 3) not quite symmetrical, being markedly 

 convex on the left side and concave on the right, abruptly bent near the middle, umbo 

 almost central, situated slightly nearer to the upper extremity of the valve ; form 

 linear, the upper and lower regions forming an angle of about 112° ; inner margin 

 curved ; the lower region of the valve a little wider than the upper ; sides of valve 

 sharply inflected and almost flat. The roof of the carina is very narrow above the 

 umbo, and from the umbo downwards is somewhat wider. The valve is not divided 

 off into tectum, parietes, and intraparietes, but these parts are fused. The whole 

 exterior surface is ornamented with raised ridges, which radiate from the umbo, and 

 are much coarser on the roof of the carina than on its sides. These ridges are crossed 

 by finer raised ridges, which follow the outline of the valve, giving the surface 

 a cancellated appearance. Inner surface of valve deeply concave. 



Tergum. A right tergum (Fig. 4) found at the same locality and horizon as the 

 carina, agrees so well with the homologous valve associated with the carina of 

 S. Darwinianum figured by Bosquet (1854) that I propose to describe it here as 

 belonging to it. 



Tergum obtusely angular in general outline, narrow, about two and a half times as 

 long as wide, ornamented with several irregular, raised longitudinal ridges. Apex 



