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Show 1873.] MR. A. G. BUTLER ON THE GENUS ACROSOMA. 427 50. ACROSOMA BULLATUM. Plectana bullata, Walckenaer, Apt. ii. p. 191. n. 63 (1837-39). "Guyana, Cayenne" (Walckenaer). Approaches A. fissispinum in the character of its spines. 51. ACROSOMA RACEMINUM, n. sp. Cephalothorax elongated, rugose, somewhat expanded behind ; caput prominent; oculiferous tubercles very prominent; femora of legs coarsely rugose; abdomen elongated, subovate, with deep sinus in front, emitting on either side a small obtuse spine or prolongation ; the entire posterior three fourths of the abdomen are almost concealed by a double cluster of large bulbous protuberances twenty in number, arranged in a waved double series on either side with their apices turned upwards or outwards ; ventral surface rugose, wrinkled, with a large globular protuberance behind spinnerets. Colours. Cephalothorax, falces, maxillae, and labium reddish castaneous ; sternum fulvous ; legs reddish castaneous, banded with darker castaneous ; abdomen dirty testaceous, the apices of the bulbous protuberances reddish ; ventral surface fulvous, with region of spinnerets brownish. Orinoco. One specimen. B.M. Seems allied to A. bullatum. 52. ACROSOMA MAMMILLATUM, n. sp. Cephalothorax as in preceding species; abdomen broader, with deeper sinus in front, but similar prolongations ; the twelve anterior protuberances converted into short acutely tipped spines-two in the centre of abdomen, directed forwards and inwards, the others projected irregularly outwards from the sides ; the six posterior arranged in a single vertical series of three at the end of the abdomen and consequently at some distance from the others; ventral surface with a hemispherical protuberance at back of spinnerets. Colours. Cephalothorax dirty reddish testaceous, with eye-eminences, two spots forming a square with the lateral eye-eminences, and a submarginal streak black; falces and labium pitchy ; sternum testaceous ; maxillae and legs reddish testaceous, more or less banded with dull black ; abdomen ochraceous, spotted all over with black. Santarem (Bates). One specimen. B.M. Allied to the preceding species. 53. ACROSOMA STELLATUM. Plectana stellata, Walckenaer, Apt. ii. p. 171. n. 32 (1837). " Carolina " (Walckenaer). Seems to belong to the A. bullatum group. 54. ACROSOMA INCISUM. Plectana incisa, Walckenaer, Apt. ii. p. 195. n. 71 (1837-39). " Brazil" ( Walckenaer). Seems from the description to approach A. bullatum; but |