Cretaceous ana ierliarij Cirrlpedes. 195 



Terguvi{V\. WW. fig. 13) subrhomboidal, elongate, mode- 

 rately convex transversely ; occludent and n|)|)er carinal 

 margins t'orinin<? tojj;etlier less than a right angle, and they 

 are al)out halt" the length of the lower carinal and scutal 

 margins. A Hat-topped ridge, innch steeper on the carinal 

 side, extends in an almost straight line from the apex, widens 

 considerably towards the basal margin, and its obliquely 

 truncated extremity is almost parallel to the upper carinal 

 margin. 



Carina (PI. VIII. fig. 12) much elongated, slightly bowed 

 inwartis or outwards, flatly arched transversely, obscurely 

 cariuate, with its basal margin almost rectangular. The 

 apical half of the valve is much thickened, and its inner 

 portion is flat and in line with the lateral margins ; a com- 

 paratively wide portion of the lower part of the valve at the 

 inner margins is marked with growth-lines, showing that 

 the valve overlapped the terga to some extent. 



Rostrum (PI. VIII. fig. 18) triangular, not quite so wide as 

 liigh, strongly convex transversely, with the apical half 

 strongly incurved, and a wide, prominent, rounded, median 

 ridge extending from the apex to the slightly convex basal 

 margin, where it is slightly produced. On the inner surface 

 there is a central depression evidently serving for the 

 reception of the rostral angles of the scuta ; and a slight 

 ridge extends from each lateral angle to a point about one- 

 third of the length of the valve from the apex, and above 

 this ridge the valve is marked by growth-lines, which show 

 that the valve overlapped the scuta to some extent. 



Rostral latus (PI. VIII. figs. 17, 19) obliquely triangular, 

 about one and a half times as wide as high, strongly convex 

 transversely, with the apical half strongly incurved, basal 

 margin concave in the middle. On the inner surface a well- 

 dcHned ridge extends from the apex to about half the length 

 of the valve, and is there met by two fnrther ridges extending 

 from each basi-lateral angle; the valve is thus divided into 

 three almost equal portions, of which the basal one is 

 smooth, and the two upper portions are marked with growth- 

 lines and must have overlapped the rostrum and median 

 latus respectively. 



Median latus (PI. VIII. fig. 20) obliquely triangular, 

 slightly wider than high, almost flat transversely, with the 

 apical portion very slightly incurved, and the lateral margins 

 somewhat raised to form flat-topped ridges. On the inner 

 surface the valve is divided off" by ridges, as is the rostrum, 

 except that the median ridge extends only one-third the 



13* 



