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12. Balanus auricoma n. sp. PI. XVIII, fig. 20 — 22, PI. XIX, fig. 1 — 7. 



Shell tlatly-conical, colour reddish, vvith darker red longitudinal lines. Radii narrow, with 

 slightly oblique summits. Opercular valves furnished with golden hairs along occludent margins. 

 Scutum without adductor ridge, and with the articular ridge only slightly prominent, tergum 

 narrow, with distinctly dentated scutal margin. 



The shell is flatly-conical, the orifice rather small, of elongately-pentagonal shape and only 

 very superficially toothed. The surface of the valves is feebly ribbed longitudinally, the outer 

 margin at the basis, in consequence, not smooth, but superficially lobed. The specimens (PI. 

 XVIII, fig. 20) were found attached to the surface of calcareous stones in close proximity of 

 each other. The colour is reddish, darker red lines running along the ribs from the orifice 

 to the basis, red spots being, moreover, scattered over the surface. The radii are narrow, 

 elongate, triangular, their summits slightly oblique. They are distinctly striated longitudinally. 

 Parietes and radii without pores (PI. XVIII, fig. 21), and no pores seen in basis. 



The scutum (PI. XVIII, fig. 22, a and c, PI. XIX, fig. ia) has the occludent 

 margin straight, and its tergal margin can hardly be said to be hollowed ont. The outer 

 surface is only indistinctly ridged. The shell as a whole is not flat, but somewhat bowed : 

 seen externally, the apical part is slightly lifted up. On the inner surface the articular*ridge is 

 not very prominent, but extends along a large part of the tergal margin ; the adductor ridge 

 is not to be seen, and the pit for the depressor muscle is triangular, rather broad and shallow. 



The tergum (PI. XVIII, fig. 22, ó and d, PI. XIX, fig. 1 ó) is narrow, has the scutal 

 margin straight and unusually distinctly dentated, and the carinal margin short and strongly 

 convex. The basal margin slopes gradually into the posterior margin of the spur; although situated 

 close to the basi-scutal angle, the spur forms a clistinct angle with the antenor part of the 

 basal margin. Externally there is a shallow furrow between the spur and the scutal margin; 

 on the inner surface the articular furrow extends over a large part of the shell along the scutal 

 margin. The crests for the depressores are strongly developed; a large part of the interior 

 surface of the valve is colourecl beautifully rose-red. 



The epidermis covering scutum and tergum is very persistent and of a golden-yellowish 

 colour; it is covered, especially along the occludent margins of both valves, with numerous 

 long and rather stiff chitinous hairs of yellowish-golden colour. 



The study of the animal's body yielded the following results : 



Mout h. Labrum (PI. XIX, fig. 2) with shallow notch, the margin of which is thickened, 

 especially at the bottom. Three strong teeth on each side. Outer margin of lateral parts 

 nearly straight, and furnished with very delicate hairs or ciliae. 



Pal pi: elongately-oval with the superior margin straight, and the inferior strongly 

 curved. Long hairs on outer surface distributed over large part of surface, near the free extremity 

 and along the inferior margin. Hairs on superior margin numerous, slightly increasing in length 

 towards the free extremity. Hairs on inner surface disposed in a row which is parallel to the 

 superior margin, and at a short distance from it, curling over free edge of labrum, when the 

 palpus is not uplifted. 



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