100 Mr. A. G. Butler on new. Species of Ceerostris. 
XI.—On some new Species of Spiders of the Genus Coeros- 
tris from Madagascar. By Arruur G. Butter, F.L.S., 
F.Z.8., &c., Assistant-Keeper, Zoological Department, 
British Museum. 
[Plate VI.] 
In a large collection of Spiders recently obtained by the Rev. 
Deans Cowan in Madagascar I detected an unusual number 
of forms of this interesting genus of Gasteracanthide. In 
addition to female specimens of C. mitralis, avernalis, and 
stygianus*, of which figures have been published, I found 
females of a species ailied to C. tuberculosa of Vinson and 
sexcuspidata of Fabricius ; also the female of a fine species 
apparently allied to C. Keyserlingit of Caffraria, a species 
near to C. Wahlbergit in both sexes, with one or two others 
of less interest. 
1. Cerostris extrusa, sp. nov. (PI. VI. figs. 3, 3.a, 3 6.) 
9. Cephalothorax dark piceous, rather longer than broad, 
laterally constricted and dorsally depressed behind the caput ; 
the latter twice as broad as Jong, with six tubercles, two on 
each side and two at the back; central oculiferous tubercle 
rather prominent, the eyes upon it larger than those of the 
lateral tubercles, the anterior pair decidedly nearer together 
than the posterior, the four eyes together forming a trapezium ; 
lateral eyes placed obliquely, the anterior ones being larger 
than the posterior. Abdomen chocolate-brown above, with-a 
broad, central, longitudinal, creamy yellowish band, divided 
in its basal half by a more or less defined longitudinal brown 
stripe, having parallel decreasing pinnate processes on both 
sides, the anterior and ventral surfaces yellowish testaceous ; 
the anterior and lateral surfaces are also impressed with regu- 
lar parallel lines on which are black dots; in form the abdo- 
men is elongate scutiform, subcaudate and deeply bifid behind ; 
the anterior margin is bounded by eight regular conical mam- 
moid tubercles, the last of which on each side forms the an- 
terior of three equidistant tubercles placed upon a slight pro- 
jecting process rising from the dorsal surface; the lateral 
margin, instead of curving gracefully inwards towards the 
eaudal process, is slightly interrupted in the middle by a small 
tubercle or pustule, which gives it a decided angularity of out- 
line; two other pustules are placed towards the side and at 
* It is possible that C. mtralis, var. turrigera, of Thorell may repre- 
sent highly developed examples of this species; the abdominal processes, 
however, are shorter in adult examples seen by me. 
