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Show 1902.] CRUSTACEA OF THE " SKEAT EXPEDITION." 3G9 Loc. Pulau Bidan, Penang. Two females, one with ova. Also another female, from Neris, with a small Ascidian attached to the loft sides of the 2nd and 3rd abdominal segments. 20. CcENOBITA PERLATUS M.-Edw. Coenobita perlatus M.-Edw. Hist. Nat. Crust, ii. p 242 (1837V Miers, ‘ Alert' Crust, p. 555 (1884). Loc. ------ ? Three females, from Murex. . Miers lias noted (I. c. supra) the fact that in this species " there is an oblique row of somewhat more elongated tubercles on the upper surface of the palm, occupying the place of the series of oblique ridges in C. rugosa " ; such ail arrangement I find in these three specimens. But the specimens in question being somewhat small, the tubercles on the legs are noticeably less piominent and less pearly than in typical examples; the carapace also is less rugose. B. CIRMPEDIA. X. Genus B a l a n u s da Costa. 2 1 . B a l a n u s am p ih t r it e D a rw in . Balanus amphitrite Darwin, ‘ Balanidae,' p. 240, pi. v. (1854). Loc. Patani. On pieces of wood, var communis; on Murex t var. obscurus; on Lamellibrancli shells, var. niveus. Loc. Singora. On Lamellibranch shells, var. obscurus, and var. niveus. 22. B a l a n u s am a r y l l is d is s im il is , subsp. nov. (Plate XXXIV. figs. 3-3 c.) ? Balanus amaryllis var. ? Weltner, Arch. f. Naturg. lxiii. 1, p. 270 (1897). Cf. Balanus amaryllis Darwin, ‘ Balaniclae,' p. 279, pi. vii. fig. 6 (1854); Hoek, ‘ Challenger' Cirripedia, p. 153 (1883). Loc. Kota Bharu, Kelantan. This subspecies is represented here by two distinct forms: one, the subspecies itself, of which there are seven large examples; the other a colour-variety, of which there are several smaller examples, attached to pieces of a Gorgonian. These two forms well illustrate the difficulty, which must sometimes arise, of finding a satisfactory place in the binomial system of nomenclature for certain divergent forms. Thus, in the present instance, No. I., though closely allied to the species B. amaryllis, yet shows sufficiently diveigent structural characteristics to be ranked as a distinct variety, if considered alone. But the presence of No. II. necessitates some sort of modification of this conception ; for, while exhibiting the same structural divergence, it also differs in colour arrangement: thus it becomes incumbent to form either a subvariety for No. II., or a subspecies for No. I. And in view of the fairly numerous instances in which Darwin has considered colour differences as of varietal worth (vide, e. g., P roc. Z o ol . Soc.-1902, V o l . II. No. XXIV. 24 |