18/3.] 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. Jissispinum 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 con- 

 cealed 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 pro- 

 jected 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 



