462 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol. XXV. 



Thus respiration in the dragonfly is carried out, not by the rising and 

 falling of ribs as in the mammalian thorax but by the relaxation and 

 taughtening of a lax, pleural membrane, the latter being analagous to the 

 mammalian diaphragm. 



At the end of the abdomen, the anus opens, three valvular flaps 

 protecting it, and on either side of it, will be found one or two pairs of curious 

 appendages, the " anal appendages ". ( Plate IX.) These may be very 

 short or very long, foliate, petiolate, saggitate or cylindrical and usually 

 coated with fine hairs. In some species they are present as nipper-like or 

 forcipated processes, closely resembling those seen in the Forficulidse. 

 Generally in the Anisopteridte, the inferior appendages are fused to form a 

 single process which is somewhat triangular in shape and often notched at 

 the extremity. In the Agrionidte, the appendages are very short and 

 inconspicuous although occasionally in some species, they may be abnor- 

 mally long and forcipated {e.g., Argia gomphoides). 



The Genital Organs. 



Male : The genitals of the male are primary and secondary, the former 

 being situated on the ventral surface of the 9th abdominal segment and 

 the latter on the ventral surface of the ilnd. The primary organ (Plate IX, 

 figs. 2 and 3) is a small papilliform eminence, the "seminal vesicle", lying 

 between the ventral plates of the 9th abdominal segment. It is covered in 

 by two chitinous folds, the " preputial folds ", which meet in close contact 

 over it. The seminal ducts open into the seminal vesicle, at the summit 

 of which is an ejaculatory duct or pore, the function of which will be des- 

 cribed later on. The spermatozoa are long, spindle-shaped, nucleated cells. 

 The secondary sexual organs are far more complicated structures and the 

 manner in which they functionate, is still very obscure. They consist 

 roughly, of a set of grappling hooks or tentaculse, a bulb which stores the 

 seminal fluid and a penis which apparently acts more an a swab than as 

 an injecting apparatus. The parts are so diverse in the difl'erent species 

 that it is difficult to generalise in describing them as a whole. The " ten- 

 taculae," (The "hamecons" of French writers) may consist of an anterior 

 pair of straight or curved hooks and a similar pair of posterior hooks, or 

 either of these pairs may be absent. The anterior pair are directed back- 

 ward as a rule and the posterior pair forward. In addition to these, in 

 some of the larger species, the Aeschnines, etc., there is a curious, bilater- 

 ally, symmetrical organ, the " receptaculum," shaped not unlike the clip 

 commonly used for securing papers in a hanging file. Posterior to it, is 

 found the penis, a very singular and complicated organ which varies con- 

 siderably in the difl'erent species. It is a polymorphic organ lying in the 

 middle line, with a dilated base, a long, narrow stem which is jointed in the' 

 middle to allow of the organ being bent on itself, so that when at rest, 

 the bulbous end is in close apposition to its base. (Plate IX. fig. 4, c). 

 The external surface is horny or chitinous and often grooved transversely 

 and occasionally furnished with minute hooks. The end is bulbous and 

 somewhat fleshy and in the Calopterygines furnished at its neck with long, 

 curving, tapering, membranous processes. (Plate IX, figs. I and XI.) 

 Ordinarily when at rest, the penis is folded upon itself and partially 

 concealed, its bulbous end being interned in a sac-life organ, the " bulb " 

 (Plate IX, figs. 1, o and 10. d.) which is a conspicuous object in some of 

 the Calopterygines and Gomphidjc but ordinarily not very evident in the 

 Aeschnines. (Plate IX, fig. 4, d.) The bulb either functionates as a re- 

 ceptacle for the seminal fluid or as a simple sac to protect the fleshy end of 

 the penis, in front of the latter organ and apparently serving to protect 

 it, is another curious grooved hook-like structure, the "sheath." which may 

 also functionate as a director for the penis, preventing over-extension when 



