50 Memoirs of the Indian Museum. [Vol. Ill, 



Scalpellum squamuliferum or peronii or of male organs in the female of Ihla cumingii. 

 There is therefore no proof that, in the change from the hermaphrodite to the uni- 

 sexual condition, the loss of one set of sexual organs has been a gradual change due 

 either to disuse atrophy, or to the semiparasitic habit of the male {vide supra, p. 35). 

 It appears justifiable to emphasize one point, although it has been known to 

 science since the time of Darwin, namely, that the only distinction between the species 

 Ibla quadrivalvis and cumingii lies in the fact that the large form is hermaphrodite in 

 the former and female in the latter. Experimental work on Mendelian hues has 

 suggested that the distinction between the two sexes of one species is of the same 

 nature as that between the varieties of one species. The distinction between the two 

 Iblas appears closely to resemble that between a " negative variety " of De Vries and 

 the parent species The negative variety differs from the parent species in having 

 lost one character, generally that of colour, and in Ihla cumingii the large form has 

 lost the single character of possessing male sexual organs. 



I.IST OF PAPERS REFERRED TO. 



1. Annandale, N. ''The Indian barnacles of the subgenus Smilium with 



remarks on the classification of the genus Scalpellum," 

 Rec. Ind. Mus., vol. v, p. 145 (1910). 



2. Aurivillius, C. W. "Studien über Cirripedien," Kon. Svensk. Vetenkap. 



Acad. HandL, Bd. 26 (1894). 



3. Beard, J. " Determination of sex in animal development," Zoo/. /cï/zrô., Anat. 



and Ontog., Bd. 16, p. 703 (1902). 



4. Claus. Untersuch, zur Erforschung der Genealog. Grundlage Crust. -Syst., 



1876, Vienna. (Quoted by Hoek.) 



5. Darwin, C. A monograph of the Cirripedia, 1851 — 1854. 



6. Gruvelj A. " Etude du mâle complémentaire um Scalpellum vulgare," Arch. 



de Biologie Belges, t. 16 (1899). 

 y, ,, Expeditions du " Travailleur " et dît " Talisman," Cirrhipèdes, 



1902, Paris. 

 7a. ,, Monographie des Cirrhipèdes, 1905, Paris. 



8. Hoek, P. P. C. Report on the Cirripedes collected by H. M.S. " Challenger," 



vol. X. 



9. ,, ''The Cirripedia of the Siboga-Expedition," Siboga-Expe- 



ditie, Monograph xxxia. 



10. Krohn, A. " Beobachtungen über den Cementapparat und die weiblichen 



Zeugungsorgane der Cirripedien," Arch. Naturg., Jrg. 

 : xxv, Bd. i. 



11. Smith, Geoffrey. " Rhizocephala," Monograph xxix, Fauna & Flora des 



Golfes von Neapel, 1906, Leipzig. 



12. De Vries, H. Species and varieties, their origin by mutation, 1905, London. 



