i) 
MS) 
1909.] ON THE LIFE-HISTORY OF THE AGRIONID DRAGONFLY. 5 
REFERENCES. 
(1) Bouran.—C. R. Acad. Sci. exxvi. (1898) pp. 1887-89. 
(2) Davis, J. R. A., & Fururs, H. J.—“ Patella.” Liverpool 
Marine Biological Committee Memoirs. Memoir x. (1903). 
(3) Fiscuer, P.—Manuel de Conchyliologie. Paris, 1887. 
(4) Furron, T. Wemyss.—24th Ann. Rep. Fish. Board Scot. 
(1905) pp. 179-274. 
(5) Gemnity, J. F—Anat. Anz. xii. (1896) pp. 392-4. 
(6) Lesert et Ropin.—Ann. Sci. Nat., Zool. (8) v. (1846). 
Ppa lol 2. 
(7) Mauarp, A. E.—Bull. Mus. d’Hist. nat. Paris, ix. (1903) 
pp. 270-4. 
(8) Parren, W.—Zool. Anz. viii. (1885) pp. 236-7. 
(9) Russetn, E. $.—Proc. Zool. Soc. 1907, pp. 856-70. 
(10) Semper, K.—“ Animal Life.” London, 1881. 
(11) Witucox, M. A.—Amer. Nat. xxxix. (1905) pp. 325-33. 
(12) Witson, E. B.—Journ. Exper. Zool. i. (1904) pp. 197-268. 
EXPLANATION OF PLATE XXXII. 
SHELLs oF Patella vulgata L. 
The actual lengths of the shells are as follows — 
Ist Row.—7 mm., 89 mm., 10 mm., 11 mm., 13°5 mm., 15°4 mm., 17°2 mm. 
2nd Row.—20°8 mm., 23 mm. (sexually mature), 266 mm. (about 12 months 
old), 30 mm. (15 months). 
3rd Row.—33'3 mm., 38°5 mm. (over 2 years), 40°7 mm. 
4th Row.—44'1 mm. (over 3 years), 47°3 mm. (about 4 years), 51°2 mm. (about 
5 years). 
5th Row.—53’5 mm., 61°2 mm. These two limpets are at least six years old, and 
may be more. 
3. The Life-History of the Agrionid Dragonfly. 
By Frank Barrour-Browne, M.A. (Oxon.), F.R.S.E., F.Z.8. 
[Received February 5, 1909. | 
(Plates XX XIII. & XX XIV.*) 
INTRODUCTION. 
So far as I have been able to find, the life-history of the 
Dragonfly has not, up to the present, been studied in detail by 
anyone. Various facts have been noted by different observers, 
but no one has apparently attempted to hatch the eggs and follow 
out the changes which take place during the larval or nymphal 
condition. 
The general facts in the life-history are well known. The 
perfect insect lays its eggs in the water; after an unknown 
period there emerges from the egg a sub-aquatic creature known 
as a nymph, which grows, casting its skin at unknown intervals, 
* For explanation of the Plates see p. 285. 
