CHAM^SSIPHO SCUTELLIFORMIS. 478 



Hub. — Attached to Pollicipes mitella, probably from the seas of China ; Mus. 

 Brit. 



General Appearance. — This very singular shell would not, without 

 some examination, be thought to be a cirripede. From the symmetrical 

 position of the four apertures, with the diamond-shaped orifice in the 

 middle, with the sutures on each side of the rostrum, and from its 

 depressed and circular form, this shell bears some resemblance to the 

 perforated species of Scutella. Shell much depressed, generally nearly 

 circular, with the basal margin highly sinuous and even sometimes almost 

 branched. Surface slightiy irregular, marked by fine lines of growth, 

 and covered by brown membrane. Of the four compartments, the 

 Rostrum is very narrow, triangular, and comes up to the orifice almost 

 in a point : it is rather depressed, that is, it lies rather below the level 

 of the other compartments : the straight sutures separating it from the 

 lateral compartments are distinct in the upper part, though always ob- 

 literated in old shells in the lower part : these sutures are generally 

 far plainer than those separating the lateral compartment from the 

 carina, which in most cases are obliterated and calcified together, ex- 

 cepting close to the orifice. The alee of the rostrum are not externally 

 visible, and there are no radii to any of the compartments. The 

 Carina is twice as broad as the rostrum, and is furnished with alee of 

 the usual shape, which are, to a certain extent, externally visible. 

 The Lateral Compartments are broad, being broader than the carina ; 

 they are both penetrated, down to the surface of attachment, by a hole 

 or rather tube, — the two holes standing opposite the rostral end of the 

 operculum: thecarinais penetratedbytwo rather smaller but similar holes. 

 It is these four holes which give to this cirripede its very singular 

 aspect : they are rather smaller than the orifice of the shell ; they are 

 oval, with their longer axes placed in the direction of the ray of the 

 circular shell : their manner of formation will be immediately explained. 

 The orifice is neatly diamond-shaped and broad : it is rather small 

 compared with the whole shell, and is closed by the operculum, which 

 is seated near the summit of the shell. Basal diameter of largest 

 specimen t 2 q of an inch ; few T , however, attained this size, and perfect 

 larvae were included in much smaller specimens. 



Structure of Shell. — The rostrum (fig. 4 c) is remarkable from its small 

 size, and from the plainness of its sutures, in comparison with those sepa- 

 rating the other compartments, and this is exactly the reverse of what I 

 should have expected in a compartment tending to become rudimentary. 

 Not only is the rostrum small, but the alse project to an unusually small 

 degree, and gradually slope away into the lower part of the parietes. 

 These peculiarities are even more strongly marked in very young shells: 

 thus in one of the size of a pin's head, the rostrum consisted of a minute 

 parallelogram, without, as far as I could see, any alee, and was only 

 one fourth of the size of the carina, — this latter compartment being 

 only half as wide as the lateral compartments. The carina, at this early 

 period, had quite distinct alae. 



The tubular prolongations from the four external holes are of course 

 very conspicuous on the under side of the shell (4 b) ; and their struc- 



