STUDIES IN POST-LARVAL DEVELOPMENT AND MINUTE 

 ANATOMY IN THE GENERA SGALPELLUM AND IBLA. 



By F. H. Stewart, M.A., D.Sc, M.B., Captain, Indian Medical Service, formerly 

 Surgeon Naturalist to the Marine Survey of India, Honorary Assistant in the 

 Indian Museum. 



L-SUMMARY OF PREVIOUS LITERATURE. 



1. The development of hermaphrodite and male forms of Cirripedes. 



2. Anatomy of the male. 



3. Question of sexual purity of the male and female forms. 



I. The development of cirripedes has been dealt with chiefly by Darwin (5) 

 and Hoek (8). Darwin (5, pp. 8 and 9) gave a summary of preceding literature 

 (Vaughan Thompson, Burmeister, Goodsir, Spence Bate) and described the develop- 

 ment from the nauplius, passing through the cyprid stage to the adult. In regard 

 to that portion of the metamorphosis with which we are concerned, namely, that 

 from the cyprid stage to the adult, he wrote : '' My chief examination has been 

 directed at this stage of development to the larvae of Lepas a^istralis which are of 

 unusual size, namely, from -065 to even almost -i of an inch in length. I examined, 

 however, the larvae of several other species of Lepas, of Ihla and of Balanus, with 

 less care, but sufficiently to show that in all essential points of organisation they 

 were identical." His descriptions are, of course, not based on the examination of 

 sections so that some gaps still remained to be filled up in regard to the more 

 histological aspect of the metamorphosis. He also fell into the error, which was 

 pointed out at a later time by Krohn and Claus, of mistaking the cement cells for 

 incipient o varia. 



Hoek (8, p. 5) again described the cyprid of Lepas australis and compared it with 

 the similar larva of the male of Scalpellum regium. In addition to excellent descrip- 

 tions he also published drawings of the two organisms and traced the evolution of the 

 male from the cyprid. 



Aurivillius (2) refers to the post-larval development of Scalpellum erosum, Aur., 

 5. ohesum, Aur., and some others, but confines himself to the external characters. 

 He figures the cyprid larva of 5. ohesum and that of the male of S. scorpio, Aur. {Vet. 

 Akad. Handl., vol. 26). 



My work, although it dealt with species different from those investigated by 

 Darwin and Hoek, has given results which in general do not differ from the conclu- 

 sions of these two distinguished observers. Only a brief summary of the general 

 outlines of the development is therefore given. Indeed, my chief excuse for publish- 

 ing any note on this subject lies in the fact that I have been able to obtain some 



