152 ENTOMOLOGICAL NEWS [April, 'll 



There is a trapezoidal dark mark across the dorsum of abdominal 

 segments 2-8 or 2-9, narrowly divided on the median line : and there 

 is a row of )-or (- marks, either side, concave externally. 



Mandibles short and thick, not biramous, but with a spinous tu- 

 bercle standing in the place of the outer ramus, and with a bifid palp- 

 like movable tooth upon the middle of the inner face. 



This nymph while agreeing in many respects with the two 

 preceding, differs markedly in the absence of lateral abdominal 

 gills and of mandibular tusk ; also in the sharpness of the con- 

 struction of the middle of the caudal gills dividing them as if 

 two-jointed and the greater length of the second antennal seg- 

 ment. 



There is no known Jamaican Calopterygine with which this 

 nymph can be associated. The imperfectly preserved venation 

 of one specimen shows that quadrangle and subquadrangle 

 are without cross veins. There are about 15 post-nodals, and 

 there is no brace vein to the stigma. Vein M2 arises a little 

 beyond the nodus, and is closely parallel with the radial sec- 

 tor throughout a rather undulate course. All the long diagonal 

 areas traversing the disc of the wing are occupied by single 

 cell rows, and there is a sudden considerable apical divergence 

 between veins Rs and M3. In all these characters there is 

 considerable resemblance to the Agrionine Ortholcstes, but I 

 cannot believe that a nymph so unlike all known Lestinae in 

 labium, in gills and in stature is referable to that genus. It 

 accords so well with Bay ad era, Diphlebia, etc., that I prefer to 

 believe there remains in Wagwater River, Jamaica, an undis- 

 covered Calopterygine genus, with rather sparse venation. 



As in the Anisoptera so in the Zygoptera, it is the form of 

 the labium that furnishes the most constant and reliable char- 

 acters for distinguishing the major groups. The presence or 

 absence of lateral gills is of small moment, and the form of 

 the caudal gills is unpredictable. Plate IV of this paper rep- 

 resents the group which in 1903* I recognized as a sub-family 

 under the name Vestalinae ; plate V represents another, that I 



*A genealogic study of dragonfly wing venation. Proc. U. S. Nat. 

 Mus., Vol. 26, p. 744. 



