694 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvn. 



V-shaped notch separating two low rounded lobes, each of which l)ears 

 a long, strong, straight, anteriorly directed s})ine, a short fringe of 

 hairs on the portion of the margin external to the spine. Lateral 

 lobes short, each with a long arcuate movable hook, and a smaller, 

 more slender, more arcuate, sharply pointed end hook, the inner 

 margin very tinely denticulate. 



Prothorax with the end of its dorsal disk laterally prominent and 

 acute; supracoxal processes obtuse, equal. iNIimite tubercles cover- 

 ing the sides of the thorax, and rugulations on the bases of the wings. 

 Legs long; femora and tibiae thrice banded with brown; tarsi 3:3:3- 

 jointed. Wing cases reaching the base of the fifth abdominal segment. 



Abdomen triquetral, Avidest on segments (3 and 7, slowly narrowed, 

 posteriorly; segments 2-9 of about equal length; segment 10 one-half 

 as long as the others, appendages longer than 9 and 10 together; 

 superior appendages ver}' slightly shorter than inferiors, with a round 

 apical notch and a sharp dorsal carina; laterals one-half as long, 

 straight on the external margin, convex on the internal mai'gin, 

 especially toward the tip, where suddenly contracted to a long point. 

 Dorsal hooks represented by minute triangular rudiments on segments 

 9 and 10, that of the tenth segment twice the size of that of the ninth. 

 Lateral spines on segments 6-10; on 6 minute; on T longer, l)ut hardl}' 

 reaching the apical suture; on 8 and 9 long, strong, prominent; those 

 of 9 almost reaching- the lev^el of the apex of the tenth segment; those 

 of the tenth segment short, triangular. The lateral margins of the 

 eighth, ninth, and tenth segments and of the inferior appendages 

 finely spinulose serrate. 



A single female specimen. The venation is well enough indicated 

 on its wing sheaths to allow generic determination, and but one species 

 of Staurophlebia is known. The labium is very like that of the nymph 

 of Gynacantha ., and quite different from that of other known ^Esch- 

 nime, but the tuberculate upper surface of the head and the external 

 process of the mandibles mark this as an archaic member of the 

 Gynacantha group of genera. 



Genus ANAX. 



Nymphs of this genus are common in every collection of aquatic 

 insects. They ai'e readily recognized by the shape of the head, with 

 the eyes broadh' overspreading its sides (see Plate XL, fig. 1), and gen- 

 erall}" b}" the possession of lateral spines on abdominal segments 7-9 

 only. Anax jimlus Drury is probabh" the commonest species in the 

 whole collection of uA^mphs of the National Museum, and it is certainly 

 present from a larger num))er of different localities than any other 

 species. Descriptions and figures of this n3'mph have been published 

 by both Cabot and myself, the figure by Miss Hart " being especially 



"Bull. 111. State Lab. Nat. Hist., VI, ])1. i, fig. 5. 



