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Show 394 RE V . O. P. CAMBRIDGE ON [June 1, usual character is furnished in the very distinct and strongly marked pattern on the upperside of the abdomen ; very few European species, discovered hitherto, present any thing like a regular pattern, while the majority have a merely unicolorous abdomen. I take this opportunity of again returning m y kind thanks to Mr. Emerton for allowing m e to describe and figure portions of these very interesting little Spiders, and I also make bold to express a hope that through his exertions I may soon have the pleasure of making known other new forms of the same genus. ERIGONE PERSIMILIS, sp. n. (Plate XLVI. fig. 1.) Erigone atra, Cambr. P. Z. S. 1874, p. 429 (exclude synonym there quoted). Adult male, length 1^- line. This Spider is very closely allied to E. atra, Bl. (E. vagabunda, Westr.), resembling it (as well as some other kindred species) in size, colours, general form, and structure. Its distinctness was overlooked I. c. supra; it may, however, be distinguished from that species, on a closer examination, by the caput having a median longitudinal row of three distinct tooth-like tubercles, each of which is furnished with a short bristle; the form also of the fore extremity, on the upper-side of the radial joint of the palpus, differs slightly, but characteristically (see fig. 1 e, fig. 2g, representing that of E. atra from a similar point of view) ; on the middle of the underside also of the radial joint in E. atra is a very slight, indeed, but perceptible, rudimentary tooth, or tubercle, while no trace of it appears to exist in the present Spider; the denticulation also of the humeral joint differs, the teeth not being so even in size or distribution as in E. atra; the palpal organs appear to be very similar ; but probably a lens of higher power than that under which I have been able to examine them would show some important structural differences. An adult male was received in June 1874 from Mr. J. H. Emerton, by whom it was found at Swampscott, Boston, Massachusetts, under a stone ; and a comparison recently made of the present Spider with that recorded as E. atra (P. Z. S. 1874, p. 429) proves the two to be identical. ERIGONE DENTIGERA, Cambr. (Plate XLVI. fig. 2.) Erigone dentigera, Cambr. P. Z. S. 1874, p. 429. Adult male, length 1^ line. This species is exceedingly nearly allied to E. persimilis, as well as to E. atra (Bl.); but it may be distinguished by its shorter legs and palpi, the cubital and radial joints of the palpus being much shorter in proportion; the latter (radial) joint has also a distinct conical tooth near the middle of its underside ; the form also of the fore extremities on the upperside of this joint differs, being narrower and more pointed, though still obtuse ; and the denticulation of the humeral joint differs, the teeth in the present species being fewer and blunter; the palpal organs also differ when viewed under a strong |