CORONULA. 39 



This species, though closely allied to C. diadema and easily confounded with it, I have 

 no doubt is distinct. I owe to the kindness of the Rev. Mr. Image an examination of the 

 original specimen figured by Parkinson ; and in Mr. Stutchbury's collection there is a 

 similar and more perfect specimen ; both of these resemble C. diadema in general form, 

 but have been too much worn to be positively identified. The following description is 

 drawn up from some compartments collected by Mr. Searles Wood, belonging certainly to 

 three and probably to four individuals, one of which was young ; as these specimens agree 

 in all essential respects, I feel pretty confident that the characters, by which the present 

 species differ from C. diadema, are of specific value. 



Structure of Shell. — The longitudinal ribs on each compartment (i. e. the circumferen- 

 tial transverse loops), are convex and prominent, as in C. diadema, but they are crossed by 

 more prominent ridges of growth (fig. 8a, 8e) than even in the roughest varieties of that 

 species, so that the surface of the shell is more rugged. In the three recent species — viz., 

 C. diadema, balcsnaris, and regince, the surface of the wall all round the cavities oc- 

 cupied by the whale's skin, is striated only by very fine longitudinal lines ; but here, the 

 outer portion, or that (fig. 8d) formed by the transverse loops, is crossed by transverse 

 ridges of growth, like, but less prominent, than those on the external surface of the shell. 

 The minute teeth, along the lines of junction between the transverse loops, are here less 

 regular, and can hardly be said to exist ; for the two edges are locked together by what may 

 be more strictly called minute zig-zag ridges (fig. 8d, 8e), than teeth. The exact number of the 

 circumferential plications (fig. 8b) in the wall of the shell is variable, in the same manner as 

 in the three recent species. In the rostrum which has been figured (8b, enlarged twice 

 its natural size), there is a peculiarity, probably accidental, which I have seen in no 

 other specimen — namely, that one of the transverse circumferential loops at the end of one 

 of the original folds of the wall, has ceased to be added to, and therefore may be seen 

 (rather on the right hand of the middle of the figure) to terminate in one of the cavities 

 between two adjoining folds. The sutural edges of the compound radii (d, fig. 8b) 

 are about as thick as, or rather thicker than, in C. diadema; for in the middle part 

 they do not reach to the sheath by about half the thickness of the compartment. In the 

 same manner as in C. diadema and regince, each ala here rests, not on the internal surface 

 (as in C. balanaris, and in all other Balanidse) of the radius, but on a special plate (<?, fig. 

 8b, 8c) ; but in C. -barbara, instead of there being a deep chamber, running up to the apex 

 of the compartment, between the radius and the special plate, this part is filled up almost 

 entirely by solid shell. Although the extent to which this chamber is filled up varies a little, 

 and although its depth varies a little in C. diadema, yet there is a marked difference between 

 the specimens of this latter species, in which the chamber is most filled up, and those of 

 C. barbara, in which it is least filled up. The alse are thick, as in C. diadema, and their 

 sutural edges have a central ridge, sending off on both sides sinuous crests. The basal 

 margins of the alee are not short compared with their upper margins, and therefore the 

 whole ala is not wedge-formed (fig. 8c); and in this rather important respect C. barbara 



