422 BALANIDzE. 



The species here described, though near 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 identi- 

 fied. 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 differs from C. diadema, are of specific 

 value. 



Structure of Shell. — The longitudinal ribs on each compartment 

 (i. e. the terminal transverse loops), are convex and prominent, as in 

 C. diadema, but they are crossed by more prominent ridges of growth 

 than even in the roughest varieties of that species, so that the surface 

 of the shell is more rugged. In the three previous species, the surface 

 of the wall entirely round the cavities occupied by the whale's skin, 

 is striated only by longitudinal very fine lines ; but here, the outer por- 

 tion, or that (fig. 6) formed by each transverse loop, is crossed by trans- 

 verse 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 than teeth. The 

 exact number of the circumferential plications in the walls is variable 

 in the same manner as in the three foregoing species. The sutural 

 edges of the radii are about as thick as, or rather thicker than, in 

 C. diadema. As in this latter species, and in C. regince, each ala 

 rests, not on the internal surface (as in C. balcenaris, and in all 

 other Balanidse) of the radius, but on a special plate ; but in C. 

 barbara, instead of a deep chamber, running up to the apex of the 

 compartment, being left between the radius and ala, 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 aloe are thick, as in 

 C. diadema, and their sutural edges have a central ridge, sending off 

 on both sides sinuous ridges. The basal margins of the abe are not 

 short compared with their upper margins, and therefore the whole ala 

 is not wedge-formed ; and in this rather important respect C. barbara 

 resembles C. baUenaris (PI. 1(5, fig. 3), and differs from C. diadema 



