36 Memoirs of the Indian Museum. [Voi.. Ill, 



large form of 5. cumingii has no penis and appears to be devoid of any male organs. 

 We have then in these two forms a male and a female, which have evolved from the 

 hermaphrodite condition only comparatively recently, and in which, if anywhere, we 

 would expect to find some trace of the lost female and male organs. 



A large number of excellently preserved specimens of Scalpe Hum squamuliferum 

 bearing numerous males was stored in the ''Investigator" collections in the Indian 

 Museum, and I obtained a considerable number of Ihla cumingii on the reefs of 

 Diamond Island off the coast of Burma during the winter of 1909. I was also so 

 fortunate as to obtain an excellent specimen of the male of Scalpelhim peronii for 

 comparison with those of 5. squamuliferum. 



The development of the ovaries and testes of the hermaphrodite was followed out 

 in 5. squamuliferum. 



The determination of the species of the specimens used is in all cases the work of 

 my friend Dr. Annaudale, to whom my thanks are due for much assistance in this 

 investigation. For the definition of the species this author's work should be con- 

 sulted (i). 



II. — Post-larval development of Scalpellum squamuliferum , Welt., and anatomy 

 of the male. 

 A. — General outlines of the development. 

 (i) The hermaphrodite — 

 (i) The pupa. 

 (2) The young adult. ^ 

 (ii) The male— 



(i) The pupa. 



(2) The young adult. 



(3) The adult. 



B. — Histology and development of the organs of the peduncle, 

 (i) The vesicular spaces of the peduncle of the pupa. 



(2) Rostral duct and lymph spaces of the adult. 



(3) The connective tissue cells and fibres. 



(4) The yolk. 



(5) The cement cells and ducts. 



(6) The ovaries. 



{6a) Absence of rudimentary ovaries in the male. 



(7) The cells of unknown function. 



III. — Absence of rudimentary ovaries in the male ot Scalpellum peronii. 

 IV. — Anatomy of the male of Scalpellum bengalense. 



' The term adult is used for all the stages after the casting off of the pupal coverings and the 

 extension of the capitulum on the peduncle. This is, of course, not pedantically correct since in the 

 earlier of these stages the animal is not truly adult, it has, however, assumed the outward form of 

 the adult. 



