114 Prof. W. B. Benham — A Giant Fossil Cirripede. 



from this, and a small rectangular portion broken off the base 

 which does not affect the shape or measurements, the valve is entire. 



The basal margin is straight; the lateral and occludent margins form 

 right angles with it, and are therefore parallel for the lower third 

 of their course. The occludent margin, as a whole, is a continuous 

 convex curve ; while the other margin of the main plate is doubly 

 curved, so as to form an ^ -shaped line, which is at first parallel 

 with the occludent margin, then bends away from it, and finally 

 curves gently towards it, so that a blunt apex is formed. 



The surface of the plate is nearly flat from side to side in its 

 proximal region, but is distinctly convex as the distal extremity is 

 approached. Moreover, when viewed from the side, the plate 

 exhibits a gentle ^ -shaped bend, the middle of it being concave out- 

 wards, the upper and lower ends convex. 



The lines of growth are transverse, nearly straight, and are 

 sufiSciently prominent over the greater part to form slight ridges, 

 but these become evanescent towards either end, and at the same 

 time the growth-lines become closer together, especially as the basal 

 margin is approached, where they are very crowded. 



The ' flange ' or tergo-lateral region of the scutum is very much 

 inflexed, forming, as I have stated, an angle of about 115° with the 

 main plate ; it is somewhat thinner than the latter, and is triangular 

 in form ; the apex of the triangle, the tergo-lateral angle, i.e. its 

 widest part, where it is 20 mm. across, is at the same level as the 

 widest part of the main plate ; the proximal side (lateral margin) 

 passes down and soon becomes nearly parallel to the side of the 

 plate, whilst its distal side (tergal margin) is shorter and passes to 

 the apex of the main plate. 



The flange differs in appearance from the plate itself, owing to 

 the direction and character of the lines of growth ; these are very 

 fine and close together, their general course is longitudinal, but 

 gradually curving outwards to reach the tergal margin, where their 

 ends constitute a slight ridge ; this margin is, I believe, the true 

 uninjured edge. In thus curving outwards a small smooth bay is 

 left on the proximal side of the tergo-lateral angle. 



I have been unable to examine the inner surface of the valve, 

 as it is closely attached to the matrix, but the concavity extends 

 up to the apex. 



The following measurements were taken : — 



(c) The nostrum (?). (PI. X, Figs. 8-9.) 



This valve is undoubtedly one of the median plates of the inferior 

 series ; it may be either the rostrum or sub-carina. It is much 

 smaller than the preceding valves, is quite symmetrical and hastate 



