1873.] MR. A. G. BUTLER ON THE GENUS ACROSOMA. 421 



but also vertical ; the other six at end of abdomen — the first two 

 longest, bent almost horizontally downwards over the abdomen and 

 widely divergent, the second pair springing laterally from the posterior 

 angles of the abdomen, the third pair immediately below the origin 

 of the second, springing from the ventral surface backwards, and 

 slightly divergent : ventral surface with three or four longitudinal and 

 transverse submarginal sulci. 



Colours. Cephalothorax black, with testaceous margin ; falces and 

 maxillae black above, becoming pitchy towards their extremities ; 

 labium ochraceous, clouded with brown ; sternum and legs black ; 

 abdomen dark red above, coarsely punctured in the centre ; spines 

 pitchy ; ventral surface brownish red, with regions of spinnerets and 

 epigyne blackish. 



Para {Wallace). One specimen. B.M. 



A remarkable species, allied to A. macracanthum of Walckenaer. 

 It differs entirely in the relative length of the spines — first pair 

 1 line, second lj line, third 3 lines, fourth 2 lines, fifth \\ line. 



5. ACROSOMA SPINOSUM. 



Aranea triangulari-spinosa, De Geer, Insectes, vii. p. 321, pi. 39. 

 f. 9, 10. 



Aranea spinosa, Linnaeus, Syst. Nat. p. 1037. n. 47 (1766). 



Plectana spinosa, Walckenaer, Apt. ii. p. 172. n. 33 (1837). 



Sp. ead. ? Para (Grahame). B.M. 



6. ACROSOMA VIGORSII. 



Acrosoma vigorsii, Perty, Delect. Anim. p. 194, pi. 38. f. 8 (1830) ; 

 Koch, Arachn. vi. p. 123, pi. 209. f. 520 (1839). 



Para (Bates). B.M. 



7. Acrosoma armatum. 



Plectana armata, Walckenaer, Apt. ii. p. 179. n. 43 (1837). 

 Acrosoma armatum, Koch, Arachn. xi. p. 65, pi. 376. f. 885 

 (1S45). 



Haiti (Tweedie). B.M. 



8. Acrosoma forcipatum. 



Acrosoma forcipatum, Thorell, (Efvers. Vetensk. Akad. Forhandl. 

 xvi. p. 300. n. 1 (1859, edit. I860); Eug. Resa, Zool. Arachn. i. 

 p. 25(1868). 



"Cuba" (Thorell). 



Seems allied to A. armatum, Koch. 



9. Acrosoma aculeatum. 



Aranea aculeata, Fabricius, Ent. Syst. ii. p. 417. n. 37. 



Aranea elongato-spinosa, De Geer, Ins. vii. p. 323, pi. 39. f. 11, 12. 



Plectana aculeata, Walckenaer, Apt. ii. p. 180. n. 44 (1837). 



Surinam. 1 B.M. 



The type of this species is in the Banksian Collection. 



