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case in the other specimens of this species. The specimens belonging to ibis latter form were 

 found at Station 164. They are characterised also by the shape of the tergum, the scutal margin 

 of which is not straight, but somewhat convex, vvhich makes this valve much broader than in 

 the ordinary form of the species (PI. XVIII, fig. 2a and ff). I intended at first to describe this 

 form as a variety of this species; since I found afterwards, however, that some specimens from 

 the same locality show these differences in a smaller degree, and others not at all, I prefer 

 to point out the variability without proposing a special name for the form that seems to 

 show this particularity in the highest degree. 



There remains no doubt in my mind that this form really corresponds with the species I 

 described in the Report on the Cirripedia of the Challenger as D. socialis. As regards the 

 important difference between the definition given in the report of 1883, and the description 

 given here, namely that I ranged the species there under those that have the parietes permeated, 

 1 now find that such pores are absent. I have already explained on p. 192, how this error 

 may have arisen. 



Further, at another Station, a few very small specimens of a Ha/anus were collected which 

 1 suppose to belong also to this species. Their opercular valves are wanting; the diameter 

 near the basis of the' largest specimen of the sample measures at the most 3 mm. ; the shells are 

 white, have large orifices; their alae and radii show the same shape as in B. socialis. They 

 were found attached to small Gastropodous-shells (ScalariaY), which were collected at: 

 Stat. 205. Lohio-bay, Buton-strait. Depth 22 m. Bottom : sandy mud. 



11. Balanus maldivensis Borradaile. PI. XVIII, fig. 13 — 19. 



BORRADAILE, L. A., Marine Crustaceans. Parts IV — VII in "The Fauna and Geography of 

 the Maldive and Laccadive Archipelagoes". Vol. I. Part 4. 1903. p. 442, fig. 11S. 



This species, which according to Borradaile, occurs in S. Nilandu Atoll (Maldive or 

 Laccadive Archipelagoes) seems to be a rather common species in the Malay Archipelago. 

 Borradaile's description in the main is exact — a somewhat more extensive one, however, will 

 not be judged superfluous. 



It is a species (PI. XVIII, fig. 13) with thick solid walls of a conical or steeply-conical 

 shape; it is often somewhat compressed laterally; the surface of the parietes looks gnarled and 

 often ringed, but not regularly ribbed. The radii are elongately-triangular, having the summits 

 broad and nearly horizontal, and terminating downwards in a point. The summits of the radii 

 are, moreover, straight or slightly concave, the alae, in the latter case, extending slightly bevond 

 the radii. The outer surface of the radii is indistinctly striped horizontally, and lies somewhat 

 deeper than that of the compartments, which gives a very typical appearance to the shell. 

 Orifice oval when seen from above, with the carinal extremity pointed, and the rostral rounded 

 or rhomboidal. Parietes and radii without pores, the inner side of the parietes strengthened by 

 longitudinal ribs. Basis also without regular canals; at the circumference, however, shallow pores 

 are seen beginning in the intervals between the bases of the ribs placed against the parietes. 

 It is a small species: the diameter of the larger specimens measures from 6 — 7 mm. near the 

 basis, their height from 4 — 5 1 /., mm. 



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