380 BALANID^flE. 



first sub-variety, together with the commonest accompanying variety 

 of tergum, I find it quite impossible to assign to it a specific character ; 

 if, on the other hand, we consider the scutum of the third sub-variety 

 by itself, nothing can appear more distinct ; but I must repeat, there 

 can be hardly a shadow of doubt that the three sub-varieties of scutum 

 here described, graduate into each other, and are specifically identical. 



Var. (7), fig. 6 r. — Hab. Probably Philippine Archipelago, associated 

 with Balanus quadrivittatus. — There can be hardly any question of this 

 being specifically identical with the last variety. It inhabits a different 

 coral. All the specimens were of small size. The walls are not so thin, 

 and the internal ribs not so prominent as in var. 6. The sheath is either 

 white or dull purple ; I can, in short, point out no difference in the shell 

 from the typical var. 1. The scutum is not so much elongated 

 transversely as in var. 6, and the basi-tergal corner is more cut off, — 

 in w T hich respect it resembles the common varieties. The adductor 

 ridge is largely developed, so as to be just visible when the valve is 

 viewed from the outside, in a degree between the first and second sub- 

 varieties of var. 6 : but the most singular character is the larger de- 

 velopment of the tooth near the rostral angle, and this was the case in 

 the same degree in all the specimens which I examined. The tergum 

 resembles that rather unusual sub-variety of var. 6 (fig. G q), which 

 has the scutal margin and the one side of the spur forming a straight 

 line. It appears to me that it would be absurd to consider these slight 

 differences, in parts unquestionably subject to much variation, as spe- 

 cific, when we are almost forced to admit that the much greater differ- 

 ences in the three sub-varieties of var. 6, are not of specific value. 



Far. (8). — Hab. Unknown, Mus. Cuming. — I have seen only a 

 single specimen of this, and refer to it on account of var. 11. The shell 

 is rather steeply conical, with distant and prominent ribs ; the radii are 

 narrow ; the walls are not permeated by pores ; the colour is pale 

 purple. Altogether its external appearance is very different from that 

 of the foregoing varieties ; but the scuta are identical with those of 

 var. 1, excepting that the rostral tooth is rather larger, being nearly as 

 large as in the last, var. 7 The tergum precisely resembles that in 

 some specimens of var. 2. Hence this variety differs from the first two 

 varieties only in the shade of colour, the external shape, and the greater 

 prominence of the external radiating ribs of its shell. All these 

 characters are variable in the several foregoing varieties, and they have 

 been found, as yet, insufficient to discriminate species in any genus of 

 sessile Cirripedes. 



Varieties with the Scuta and Terga calcified together. 



Var. (9), PI 14, fig. Gs [C. spimdosa, of Leach (!)]— Hab. Un- 

 known. — The shell is undistimmishable bv a single character from 

 many specimens of the first, third, and fourth varieties ; it is not per- 

 meated by pores. The scutum and tergum, with the exception of 

 the one striking difference of their being calcified together without 

 any trace of a suture, are identical with those of var. 3, as may be seen 

 by comparing the figures Gh and Gs. Hence to separate this form 

 specifically from var, 3, we should have to rely solely on the calcifi- 



