CORONULA BARBARA. 421 



end and C. balcenaris at the other. The sinuous plates, forming the 

 lower part of the radius, are coarser and stand rather further apart 

 than in C. diadema. The alae are thick, and have the same outline, 

 being narrow at their basal margins and broad at top, as in C. diadema, 

 with their sutural edges similarly constructed : the basal edge of the 

 sheath likewise projects freely. 



Operculum. — This resembles most closely that of C. diadema. There 

 are no rudiments of terga. The scuta cannot be distinguished from 

 those of C. diadema. 



Mouth. — The labrum has a row of inwardly curved little teeth along 

 the whole crest, and these I did not notice in C. diadema : there is only 

 a trace of the prominence on the outside at the bottom of the central 

 notch. The hairs on the basal exterior margin of the palpi are mo- 

 derately long. The mandibles have five teeth. In the Cirri, the first 

 pair resembles in its peculiar structure those of C. diadema. In the 

 sixth pair, however, the segments support only three pairs of main 

 spines : but the specimen was not very large, and probably in old 

 specimens there would have been four pairs. 



Summary. — The present species differs from both the foregoing only 

 in its rather more conical and straight-sided outline, smooth, frosted 

 surface, and in the narrowness of the sutural edges of the radii, and 

 consequent large size of the chambers between the radii and alae. It 

 resembles C. diadema, as far as the shell is concerned, in the external 

 ribs or transverse loops having their lines of junction serrated and 

 in being solidly filled up — in the shape of the orifice and of the 

 internal cavity of the shell — in the shape and structure of the alae — 

 and in the basal edge of the sheath being free. It comes nearer to 

 C. diadema than to C. balcenaris in the structure of the radii. It 

 differs from C. diadema, and comes nearer to C. balcenaris, in the ex- 

 ternal ribs being flattened, instead of being convex, and in the lines 

 of growth being very delicate. But as it resembles C. diadema in the 

 several foregoing characters of its shell, in the opercular valves, in all 

 parts of the mouth (excepting the labrum), and in the cirri, it is very 

 much more nearly related to that species than to C. balcenaris. 



4. CORONULA BARBARA. PI. 15, fig. 6. 



Cokonulites diadema (?). Parkinson, Organic Remains (1811), 



vol. 3, p. 210, PL 16, fig. 19. 



Shell {probably) crozvn-shaped, with longitudinal convex 

 ribs, having their edges crenated, and their surfaces rugged, 

 both externally and internally, with transverse ridges : radii 

 moderately thick ; the spaces between the radii and the alee 

 solidly filled up. 



Fossil in Red Crag, (Bawdsey and Sutton) ; Mus. S. Wood and Geological 

 Society. 



