32 FOSSIL CIRRIPEDIA. 



B. stettaris, of Bronn ; but as Bronn distinctly states, that in his species the parietes are 

 porose, and as such is not here the case, this cannot possibly be that species : these 

 specimens did not possess their opercular valves, and therefore cannot be identified with 

 certainty. 



General Appearance. — Shell conical (fig. 5a, 5b), with the orifice rather large, and 

 rhomboidal. The surface is very smooth, except in var. (b) from the Continent, in which it 

 is rugged and longitudinally folded. The colour is ochreous-brown (chiefly no doubt 

 derived from the imbedding substance), tinged with red. The radii often have a much 

 darker and more distinct red tint ; they are sometimes longitudinally striped with dirty 

 white. The radii are broad, with their summits straight, and very slightly oblique ; in 

 var. b, however, they slope at an angle of about 45°. Basal diameter of largest specimens 

 •6 of an inch ; but this is an unusual size. 



Scuta, with the growth ridges little prominent. Internally (fig. 5/, from a young 

 individual) the articular ridge is moderately prominent, with its lower end very obliquely 

 rounded off; there is no adductor ridge ; there is a minute pit for the lateral depressor 

 muscle. Terga, with a slight longitudinal depression extending down to the spur ; spur 

 short, with its lower end almost square or truncated, about one fourth of width of valve, 

 and placed at about half its own width from the basi-scutal angle. Internally (fig. 5g) 

 the articular ridge is prominent ; the crests for the tergal depressores are feebly developed. 



Parietes, moderately thick and generally strongly ribbed internally, without parietal 

 pores. Radii, wide, with their upper margins straight, not smooth or rounded, and very 

 slightly (or, in var. b, moderately) oblique ; their sutural edges have well-developed septa, 

 which are denticulated : the interspaces between the septa are filled up solidly. The alee 

 have their upper margins oblique : they are only slightly, and sometimes not at all, added 

 to above the level of the opercular membrane : their sutural edges are smooth. The basis 

 is thin, but plainly porose. 



Var. {a) (fig. 5c, 5d). — With respect to this remarkable variety, any one would at first 

 think it specifically distinct. The shell is much compressed, or elongated in the rostro- 

 carinal axis, sometimes to a great degree; I have seen a specimen "25 of-an inch in this 

 axis, and only *1 in its broadest part ; but this is a very unusual degree of elongation. The 

 most remarkable character is the extraordinary narrowness of the carina, of the carino-lateral 

 compartments, and of the rostrum, compared with the great breadth, especially along the 

 basal margin (fig. 5d), of the lateral compartments. The radii are of unusual breadth. The 

 tips of the rostrum and of the lateral compartments are a little arched in, tending to make 

 the shell somewhat globular. The true basis is extremely narrow (fig. 5d) : it is deeply 

 grooved, from clasping the thin, cylindrical stem of the coral to which it has adhered ; and 

 I have seen specimens in which the opposite edges of the groove had met, a tube having 

 been thus actually formed. From the grooved basis, and from the elongation of the shell 

 in the rostro-carinal axis, this variety presents so close a general resemblance to Balanus 

 calceolus, and its allies, that I have seen it in a collection arranged on the same tablet with 



