[419] Mr. Ch. Fraser, in ‘Proc. Zoolog. Soc.’ 1869, p. 3. I am indebted to Mr. Bate for the statement from Dr. Power.
[420] Claus, ‘Die freilebenden Copepoden,’ 1863, s. 35.
[421] ‘Facts and Arguments,’ &c., p. 79.
[422] ‘A History of the Spiders of Great Britain,’ 1861-64. For the following facts, see p. 102, 77, 88.
[423] Aug. Vinson (‘Aranéides des Iles de la Réunion,’ pl. vi. figs. 1 and 2) gives a good instance of the small size of the male in Epeira nigra. In this species, as I may add, the male is testaceous and the female black with legs banded with red. Other even more striking cases of inequality in size between the sexes have been recorded (‘Quarterly Journal of Science,’ 1868, July, p. 429); but I have not seen the original accounts.
[424] Kirby and Spence, ‘Introduction to Entomology,’ vol. i. 1818, p. 280.
[425] Theridion (Asagena, Sund.) serratipes, 4-punctatum et guttatum; see Westring, in Kroyer, ‘Naturhist. Tidskrift,’ vol. iv. 1842-1843, p. 349; and vol. ii. 1846-1849, p. 342. See, also, for other species, 'Araneæ Svecicæ,’ p. 184.
[426] Walckenaer et P. Gervais, ‘Hist. Nat. des Insectes: Aptères,’ tom. iv. 1847, p. 17, 19, 68.
[427] Sir J. Lubbock, ‘Transact. Linnean Soc.’ vol. xxv. 1866, p. 484. With respect to the Mutillidæ see Westwood, ‘Modern Class. of Insects,’ vol. ii. p. 213.
[428] These organs in the male often differ in closely-allied species, and afford excellent specific characters. But their importance, under a functional point of view, as Mr. E. MacLachlan has remarked to me, has probably been overrated. It has been suggested, that slight differences in these organs would suffice to prevent the intercrossing of well-marked varieties or incipient species, and would thus aid in their development. That this can hardly be the case, we may infer from the many recorded cases (see for instance, Bronn, ‘Geschichte der Natur,’ B. ii. 1843, s. 164; and Westwood, ‘Transact. Ent. Soc.’ vol. iii. 1842, p. 195) of distinct species having been observed in union. Mr. MacLachlan informs me (vide ‘Stett. Ent. Zeitung,’ 1867, s. 155) that when several species of Phryganidæ, which present strongly-pronounced differences of this kind, were confined together by Dr. Aug. Meyer, they coupled, and one pair produced fertile ova.