Description of Gasteracantha rufospinosa. 

 By Geo. Marx, m.d. 



Although there are 

 over 1 70 species of 

 Gasteracantha at present 

 known and described. 

 from all parts of the 

 globe: and several species 

 are quite common in the 

 U. S., there are only 

 two males known for the 

 1 70 females. One is that 

 of Gas/, purvula, describ- 

 ed by Thorell, the other 

 that of Gast. Rogersii, 

 a. $ enlarged 9 times, b. cephalothorax of Mime. described by Cambridge, 



c. palpus, d. 9 enlarged 2 times, e. cephalothorax .. 



of same. /. $ in natural prop >r ion to 9- Irom Alnca. 



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 little 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 /w se, but more remarkable is the great differ- 

 ence in the structure between the two sexes and especially in the cephali 1- 

 thorax. 



We need not wonder that in the male all spinous processes of the 

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

 wma, 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. 



X< 1 w in G-isteracantha 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 Q it is at the vertex of the cepha'x — the lateral eyes are re- 

 el far behind the posterior middle eyes. 



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

 that it might perhaps make its abode there lor the whole period 



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

 the readers who r< side in the Southern States would study the habits of 

 this spider ami make known the result. 



