T. H. Withers — Cirripedes from the Chalk. 



25 



(I 13605), or in the other English specimens, neither does it appear to 

 'be so in the carina figured by Bosquet (1854) or that by Peron (1888). 



Scalpelltjm: longissimum, sp. nov. Fig. 5. 



Diagnosis. Tergum long, narrow, about three and a half times as 

 long as wide, widest part of valve near the base, scutal margin pro- 

 portionally very narrow, and formed by two straight lines which make 

 .an angle of about 140°. Surface of valve smooth. 



Material. A right and a left tergum, both complete, and a portion 

 of a right tergum. The complete right tergum has been crushed and 

 the pieces slightly displaced, but the left tergum, although it has 

 been broken, has been so reset that it shows its original shape. It 

 measures 24 • 3 mm. in length, and its greatest width is 7 mm. 



Holotype. — The left tergum (Fig. 5). 



Horizon and Locality. Upper Senonian, Actinocamax quadratus- 

 zone : East Harnham, near Salisbury, Wilts. 



Fig. 



5b. 



5c. 



Scalpellum longissimum, "Withers, sp. nov. External view of left tergum. 

 x 2 diam. tipper Senonian, Actinocamax quadratus-zone : East 

 Harnham, near Salisbury, Wilts. 



Id. Inner surface of same, showing portion of valve near apex marked 

 with fine transverse hues. 



Id. Section across middle of same. 



Description of Solotype. Tergum divided into two unequal portions by a well- 

 defined ridge extending from the apex to the basal angle ; the carinal portion is 

 extremely narrow and emerges from the basal angle, widening very slowly until it 

 reaches about three-quarters the length of the valve, and then rapidly narrows until 

 it reaches the apex, thus .forming an obtuse angle about one-fourth from the apex ; 

 the occludent portion in its widest part, which is at the angle formed by the 

 occludent and scutal margins, is about three times the width of the widest part 

 of the carinal portion (i.e. one-fourth from the apex) ; scutal margin formed of 

 two almost equal straight lines making an obtuse angle. Occludent portion sharply 

 bent downwards from the carinal portion, and on reaching the line from the apex to 

 the angle of the scutal margin, becomes flattened and forms a wide flat groove or 

 depression. This is bounded by a slip of about the same width, which rises sharply 

 up from the depression and forms a rounded border to the occludent margin. On the 

 carinal portion the growth-lines are very obliquely upturned, and run nearly parallel 

 to the lower part of the carinal margin, and on the occludent portion they are 

 more prominent than on the carinal portion, and follow the outline of the scutal 

 margin. On the inner surface there is an extremely narrow portion of the valve 



