from the Lower Amazons d)C. 105 



inner side. Tarsus elongate-pyriform. Bulb simple, pro- 

 duced backwards at base, its apex terminating in two membra- 

 nous pi'ominences not well defined. 



Measurements in milUm. — 6. Carap, T'O long., 6-25 lat.; 

 abd. 8-5 long., 4o lat. ; stern. 3-25 long., 3 lat. ; pedes long., 

 i. 43, ii. 37, iii. 30, iv. 42 ; art. i. 2-75— -5 -10— 3;5 — 12— 

 10*25 — 4. Comparative measurements of female the same, 

 except pedes i. 43, iv. 43. 



$ . The structure of the body is the same as that of the 

 male, except that the gibbosity of the carapace at base is 

 less pronounced. 



Vulva broader than long, consisting of a pair of shallow 

 circular spiraloid depressions, having between them poste- 

 riorly a small triangular piece. 



Spinners 6, with a cribellum before the anterior pair; 

 posterior pair slightly longer, with distinct terminal joint in 

 the male, but not so noticeable in the female. 



This large species was abundant in the neighbourhood of 

 Santarem and in the Forest, as well as at Obidos. Its habit 

 much resembles that of Leiocranum rupicola of Europe. It 

 lurks beneath stones, pieces of timber, or tiles, sitting quite 

 flat and close to the surface, darting round to the opposite 

 side with extraordinary speed, and after the fashion of a 

 *' heteropod." Several females, almost adult, were taken, one 

 adult male, and one adult female, whilst of the immature 

 numerous specimens occurred. The webbing with which 

 I found this spider connected was loose and flocculent, spread 

 over the surface of the stone ; but so rapidly did the spiders 

 retreat, that I was unable to make any observations on their 

 habits. They occurred abundantly amongst the stacks of the 

 roofing-tiles piled up near the saw-mills in the neighbourhood 

 of Santarem. 



EXPLANATION OF THE PLATES. 

 Plate ni. 



i. Cte7ius. Eyes in front of : — (a) Ctenvs Beidyi, $ ; (b) C. sinuatipes, 



5 ; (c) C. similis, §; (d) C. alhofascititus, §. 

 ii. Ctemis. YiiIte. (a) C. Heidyi, (b) C. Andreust, (c) C. Kei/ser- 



linyii, (d) C. nigriventer. 

 iii. Ctenus boUviensis. (a) Palpal bulb from beneath ; (b) central lobe ; 



(c) tibial spur of pedipalp. 

 iv. Ctenus. Vulva, (a) C. shyulis, 5; (b) C. alhofasciatus, §; (c) C. 



minor, 5> (dj C. sinuatipes, $. 

 V. Ctenus. C. minimus, S . Tibia of pedipalp, (1) from above, (2) from 



outside, 

 vi. Ctenus. Prolarsus and tarsus iv. of S . (a) C. nigritus and C. rec- 



tipes, (b) C. planipes, (c) C. serratipes, (d) C. curvipes, (e) C 



sinuatipes, (f ) C. medius. 



