Description of Gasteracantha rufospinosa. 

 By Geo. Marx, m. d. 



Although there are 

 over 170 species of 

 Gasteracantha at present 

 known and described, 

 from all parts of tlie 

 globe: and several species 

 are quite common in the 

 U. S., there are only 

 two males known for the 

 I 70 females. One is that 

 of Gast. parvula, describ- 

 ed by Thorell, the other 

 that of Gast. Rogersii, 

 n. <^ enlarged 9 times, h. ceplialothonx of same. described bv Cambridge, 

 0. palpus, d. 9 enlarged 2 times, e. cephalothorax a r ■ 



of same. /. (^ in natural prop ir ion to O. irom Airica. 



I received through the kindness of Mr. H. G. Hubbard of Crescent 

 City, Fla., a female in alcohol (fig. d) with the notice to examine the 

 ventral side and see if the little black spider, closely adhering to it, was 

 a young one, or the long looked for, male. It was difficult to separate 

 the two specimens, as the Httle one had securely fastened itself with the 

 aid of several strong threads upon the rugose surface of the venter of the 

 larger one. On examination it proved to be the male (fig. a). 



This was interesting />fr se, but more remarkable is the great differ- 

 ence in the structure between the two sexes and especially in the cephalo- 

 thorax. 



We need not wonder that in the male all .s{)inous processes of the 

 abdomen are wanting, for such is also the case in the 4 species o^ Acro- 

 soma, indigenous to the U. S ; but there is generally a certain similarity 

 preserved in the structure of both sexes, even if the cepha'x in the (^ is 

 often larger and its pars cepha. higher. 



Now in Gasteracantha the cepha'x of the male is on an entirely 

 different plan for it is here drawn out into a pointed projection over the 

 mandibles, the highest point being at the base of the p. ceph (fig. b), 

 while in the 9 it is at the vertex of the cepha'x — the lateral eyes are re- 

 moved far behind the posterior middle eyes. 



The fact that the male was found fastened to the underside of the y 

 suggests that it might perhaps make its abode there for the whole period 

 of sexual intercourse or even longer, and it would be of great interest, if 

 the readers who reside in the Southern .'^tates would study the habits of 

 this spider and make known the result. 



