28 MUSEO NACIONAL DE BUENOS AIEES. 



it froin tlie species of de Selys' second section interruptum , nigri- 

 nuchále, laterale aud clieliferum ; the coloration of tliorax and of 

 abdomen is likewise different. 



From ajjicale, latapistylum differs by the coloration of the side 

 of the thorax, by the shape of 10 and of the appendages . 



From gracile and its races (?) minarum, lancea and vidua the 

 male differs by the shape of the appendages, and, in addition, 

 from lancea hj the color of the abdomen, and from vidua by the 

 color of the thorax. Oradle is the nearest ally of latapistylum and 

 the females do not appear to differ. 



From truncatum, latapistylum differs by the shape of the pte- 

 rostigma, the larger post- ocular spots, the shape of the male ap- 

 pendages, the color of the abdomen of the female. 



From temporale, by larger size and coloration of the abdomen. 



From trimaculatum, by the coloration of the sides of the thorax 

 and of abdominal segments 8-10, and the relative lengtli and 

 shajíe of the inferior appendages of the male. 



3. Gynacanthíi biíicla Rambur. 



Ramb., Ins. Xévr., 1842, p. 213. 



One female in fragments. 



4. Gynacantha trífida Rambuk. 



Ramb., Ins. Névr., 18-42, p. 210. 



One male and one female, rather aged to judge by the color of 

 the thoraces. Both have the wings yellowish-brown thronghont, 

 in which respect they differ from the type, but I can find nothing 

 else to indícate that they are of another S23ecies. Two other South 

 American species possess similarly colorad wings ; these are ohscu- 

 ripennis Blanchard (D'Orbigny's Voyage dans l'Amér. Mérid. vi, 

 pt. 2, p. 217, pl. XXVIII, f. 3, 1837-43) and croceipennis Martin (Anu. 

 Soc. Ent. France. lxvi, p. 591, 1897), but in neither of these is the 

 abdomen constricted at the third segment, as is the case in trífida 

 and in the two j^resent individuáis. A male from Surinam by Tho- 

 rey, in the Museum of Comparative Zoology, Cambridge, Mass., 

 has similarly colored wings and seems also to be trífida. 



