(sect, f), balanus allium. 281 



oblique, but sometimes they are highly oblique : their sutural edges 

 are most finely crenated. The basis is generally flat, sometimes cup- 

 formed ; it is permeated by pores, crossed by transverse septa ; and 

 sometimes there is an underlying cancellated layer. 



Mouth: labrum with either six very small teeth, or with none. Man- 

 dibles (PL 26, fig. 5), with the third tooth a little thicker than the 

 first; fourth and fifth teeth small, but quite distinct. Maxillce 

 (PI. 26, fig. 7), with the inferior part forming a square step-formed 

 projection, bearing, one behind the other, two spines as long as the 

 upper pair ; in a young specimen of var. (a) this step-formed projec- 

 tion was absent. 



Cirri : first pair with the rami unequal by about four segments : 

 the shorter ramus has the segments very protuberant in front, thickly 

 clothed with strongly serrated spines ; the second cirrus has segments 

 moderately produced ; the third has them produced only in a slight 

 degree. The pedicels of the second and third cirri have dorsal tufts of 

 spines, but not a hairy plate prolonged over the thorax. The posterior 

 cirri have segments broader than long, bearing only two pairs of 

 nearly equally long spines ; and between each pair there is a small 

 intermediate tuft. The penis has the usual basi-dorsal point. 



B. amaryllis is a distinct and well-defined species, more 

 nearly related to B. Hameri than to any other form. 



34. Balanus allium. PL 7, fig. 7 a — 7 d. 



Shell faintly tinged with purple .- radii broad, with their 

 summits not oblique : basis not porose. Scutum with the 

 lines of growth crenated ; tergum with the spur extremely 

 shorty truncated, broad as half the valve. 



Hab. — Raine's Islet, Barrier Reef, Australia, Mus. Stutchbury. Hab. un- 

 known, attached to and coated by Porites. Mus. Brit. 



General Appearance. — Shell conical, smooth, but with the lower part 

 sometimes narrowly ribbed in lines Corresponding with the internal 

 longitudinal ribs ; tinted pale peach-blossom purple, owing to the 

 sheath being finely so coloured ; or wholly white. Radii broad, white, 

 square on the summit, hence orifice entire, ovate passing into rhom- 

 boidal. The parietal portion of the carino-lateral compartments ex- 

 tremely narrow, about one eighth of the width of the parietes of the 

 lateral compartments. Basis concave, partially imbedded in the coral. 

 Largest specimen *35 of an inch in diameter. 



There are some specimens in Mr. Cuming's collection which appear 

 to belong to this species, and are certainly very closely allied to it, but 

 not having the opercula, cannot be identified positively; the shell is 



