1 62 DESCRIPTIONS OF PREPARATIONS. 



Acta, 41, 1879; 46, 1884; Amans, Comparaisons des organes-du vol dans la 

 se'rie animate, A. Sc. N. (6) xix. 1885. 



Stridulation of Acker ontia. Moseley, Nature, vi. 1872. 



Nervous system. Chorda supraspinalis. Burger, Arch. Zool. Niederland. iii. 

 1876-77. Cattle, Z. W. Z. xxxv. 1881. Nussbaum, Z. A. viii. 1884, pp. 17, 48. 

 See works cited ante, pp. 152, 156. 



Eye. Carriere, Sehorgane der Thiere, pp. 152, 186, Miinchen und Leipzig, 

 1885. Grenacher, Sehorgan der Arthropoden, Gottingen, 1879, p. 103. Carriere, 

 :Q. J. M. xxiv. 1884 ; Id. Z. A. ix. 1886, and Hickson, Q. J. M. xxv. 1885. 



Malpighian vessels. Cholodkowsky, C. R. xcviii., xcix. 1884. 



Stigmata. Krancher, Z. W. Z. xxxv. 1880. 



Sex apparatus in Nematois metallicus. Cholodkowsky, Z." W. Z. xlii. 1885. 



Testis. Cholodkowsky, Z. A. iii. 1880; vii. 1884. Clasping organs of Rho- 

 palocera. Gosse, Tr. L. Sc. (2) ii. 1883; White, Ibid. i. 1879. Connection of 

 genitalia to heart. Landois, Z. W. Z. xiii. 1863. 



Ovary. Brandt, Das Ei, Leipzig, 1878. Female apertures. De Lacaze- 

 Duthiers, A. Sc. N. (3) xix. 1853. 



Metamorphosis. Martin Duncan, Transformation of Insects (ed. iii.), Cassel 

 and Co., London (n. d.). Sir John Lubbock, Metamorphosis of Insects (Nature 

 Series), 1874. Balfour, Comp. Embryology, i. p. 348 et seqq. Keferstein, 

 Betrachtungen iiber die Entwickelungsgeschichte der Schmetterlinge u. deren 

 Variation, Erfurt, 1880 (not seen). 



Genealogy of Insecta. Packard, American Naturalist, xvii. 1883. Brauer, 

 Verhandl. K. K. zool. bot. Gesellschaft, Wien, xix. 1869; xxviii. 1878. Id. Sys- 

 tematisch. Zoologisch. Studien, SB. Akad. Wien, xci. Abth. i, 1885 ; see Emery, 

 Biol. Centralblatt, v. 1884-85. Mayer, J. Z. x. 1876. Cf. Wood Mason, Trans. 

 Ent. Soc. 1879. 



32. COMMON CRAYFISH (Astacus fluviatilis), FEMALE. 



THE body of this Crustacean, like that of all Podophthalmata, consists 

 of two great divisions, an anterior, the cephalothorax, covered dorsally and 

 at the sides by a large continuous shield, the carapace, and a posterior, the 

 abdomen, consisting of six separate metameres or somites, and of an 

 azygos terminal flap, the telson, the last somite of the body, upon 

 which the anus is situated ventrally. The cephalothoracic carapace is 

 divisible into two regions by a well-marked curved line, with its concavity 

 looking forwards, which is known as the cervical groove. The part anterior 

 to this line corresponds to the head, the part posterior to it to the thorax, 

 and they are known respectively as cephalo- and omo-stegite. The omo- 

 stegite is marked dorsally by two longitudinal and short branchio-cardiac 

 grooves connected anteriorly by a curved transverse groove. Within the 

 area inclosed by these three grooves lies the heart. The lateral areae of the 

 omostegite, known as the branchiostegites, roof in the branchial chamber. 



