Goddard.] 208 [Oct. 2, 



at the most proximal, these appendages are a pair of horns, twisted at 

 the base; 'a pair of membranous lobes, thickly beset with hairs irregu- 

 larly arranged ; and lastly two slender horns (Fig. 6). 



We appear to have in Diplax vicina a more primitive condition than 

 in Diplax ruhicundula, in that the base which bears the appendages at 

 the penis-tip is elongated so that they arise in succession instead of 

 forming a clump. The inner horns are very probably the result of the 

 division of the fork of D. ruhicundula, and the other parts appear to be 

 homologous respectively with the hood, the twists and the banners of 

 that insect. 



In Celithemis elisa, the mesal part only of the caudal edge of the ven- 

 tral sclerite is emarginate. The hamules are inconspicuous, being but 

 little larger than the genital lobes ; their basal part is membranous or 

 but slightly chitinized and the lobes are long, stout, and of nearly equal 

 length. The framework which bears the hamules is strongly chitin- 

 ized ; its lateral projections (Fig. 8, m) are long and stout ; the part of 

 the median triangle (n) cephalad of the framework is short, but the 

 triangle extends caudad, farther than in other forms. 



In the genital bladder the two latero-cephalic triangles of the ventral 

 face are replaced by a single sclerite, somewhat cleft mesally, which 

 apparently corresponds to the two united. The bladder is attached 

 only by a small proximal neck and the dorsal aspect bears a tapering 

 triangular sclerite (Fig. 9, s), each basal angle of which is attached to 

 one side of the sclerite (w). 



As to the distal segment of the penis, the shield is a broad sclerite, 

 bearing lateral hornlike projections which point ventrad. The rmg is 

 of smaller diameter, but is very long, and has in general much the shape 

 of a boddice ; its edges meet on the dorsal lin^ but, so far as I can make 

 out, do not unite. These edges are prolonged distad into two rodlike 

 pieces (2). The fork is represented by a thick yellow sclerite, somewhat 

 bifid, which lies close beneath but is quite free from these pieces (5). 

 Laterad and proximad of the fork are a pair of tiny membranous lobes 

 apparently corresponding to the banners (4). The hood is a large mem- 

 branous lobe, thickly beset with hairs (3). 



In this species, the twists of D. rubicundula appear to be entirely want- 

 ing. It is just possible, of course, that they maj' have moved dorsad 

 and fused with the ring forming the rodlike projections of the sclerite. 

 I have, however, no evidence tending to show that this has taken place, 

 and in the absence of such evidence it cannot be assumed. We must 

 suppose, therefore, that the twists are absent and that these rodlike 

 projections are new developments. The advantage of having the gen- 

 ital bladder provided with three sclerites seems evident, so that C. elisa 

 is probably primitive, since retrogression is hardly likely to be accom- 

 plished by fusion. There seems some slight reason for believing also 

 that the condition of the fork found in this species is the original one, 

 and that the two horns found in B. vicina have arisen bv the division of 



