12 THE IMMATURE STATE OF THE ODONATA. 



long, narrow, middle third of front border somewhat produced in two triangu- 

 lar lobes, rather deeply cleft ; on each side of cleft highly developed spinous 

 processes. Legs very slender. Processes enclosing right angle ; posterior 

 longer, anterior thicker. Abdomen long ; lateral spines on segments six to 

 nine. Appendages sharp, middle one as long as the inferiors, not dee^^ly 

 notched ; laterals somewhat shorter, male projection conical. 



1. GYNACANTHA? SPECIES. 



Plate III. Fio. 2. 

 Hagen, Stettin Zeit. XIV. p. 268. 



Locality unknown, probably Brazil. Nympha^ two, male and female not 

 fully grown, types described by Hagen. Length, 42 mm. ; breadth, 7 mm. 

 A smaller nympha from Charleston, S. C, and one from Florida, and some 25 

 mm. length from Rio San Francisco, Brazil, Thayer Exp., are identical. 



Body exceptionally slender and elongated, flat. Head very flat, and 

 longer than Inroad. Eyes elongated, two thirds the length of head, narrow, 

 moderately prominent, at the hind inner angles somewhat produced ; sepa- 

 rated from occiput by straight line. Ocelli hardly discernible, space between 

 the eyes in general shape almost square. The two parts of the vertex are 

 not very distinctly marked. The lobe at the sides large and polished ; jjart 

 behiud the eyes one third the length of head; sides straight; occiput long 

 and deeply notched ; hind angles acute, and Avith polished bands separated 

 by roughened lines on upper side. Antenna? very slender, little longer than 

 head, exceptional in hoving the sixth joint longest. Mask extending to be- 

 tween hind legs, very long and narrow, enlarged abruptly at apical third 

 to twice the width of basal portion ; middle third of front border deeply 

 cleft, into two very prominent teeth, placed one on each side on the inner 

 slope of the cleft. Palpus finely denticulated, cut nearly straight at tip ; 

 hooks of palpus pi^olonged so as to more than meet ; movable hooks extending 

 beyond the base of each other, cylindrical. Prothorax nearly as broad as back 

 part of head, rounded behind. Processes enclosing right angle, posterior 

 one longer, anterior thicker. Legs slender, hind legs reaching middle of 

 seventh segment. Thorax small ; wing cases in the largest specimen, extend- 

 ing only a little be^'ond first segment. Abdomen long, slender, small at base 

 and enlarged as fiir as seventh segment ; thence tapering, smooth ; the eight 

 impressions not very distinct. The four middle ones, transverse ; dorsal band 



