234 On the Nauplius and Pupa Stage of Suctoria. 



suspected the presence of the male organs of Suctoria. In 

 1873 I myself described the testes and the spermato- 

 zoids of Sacculina and Peltogaster *. I have thus been much 

 surprised on reading that an accurate observer and distin- 

 guished carcinologist like Spence Bate still asks, " Of 

 what form is the male of Suctoria? and when does the 

 female become impregnated?" I was equally astonished at 

 the following : — " What do we know of the development of 

 Sacculina, Cletstosoma, Peltogaster^ or any of the parasitic 

 Suctoria? or as to what changes these undergo after the 

 Nauplius stage before they attach themselves as parasites to 

 other Crustacea?" for in my previous papers I made known 

 the numerous and rapid transformations imdergone by the 

 embryo of Suctoria after its hatching and before fixing itself. 

 I even mentioned that I had been led to such researches by 

 the difficulty, pointed out by Mr. Spence Bate, of preserving 

 the life of these delicate creatures. 



I regard as highly characteristic of the Nauplius of Suc- 

 toria and generally of Cirrepdia, the presence of two frontal 

 horns into which open the deferent canals of two enormous 

 glands. I know from verbal communication that Professor 

 Lacaze-Duthiers did not find these horns in the embryo of 

 Laura^ which I look upon not as a species of Crustacea but 

 as a real type of Suctoria. But I know from experience that 

 in some species of Peltogaster they can only be found after 

 careful examination ; and I am convinced that, attention being 

 directed to that point, they will be found in the embryo of 

 Laura. 



Semper and Rossman described, long before Dr. Power, 

 some species of Suctoria in which the embryo seems to hatch 

 with the ^?/^rt-form of Cirripedia. I say seems ; for, in spite of 

 the denials of Prof. Semper, I am not yet fully convinced, on 

 account of the rapidity of the first changes of these embryos, 

 that the transformation of the Naupliits into the Cypris stage 

 is not effected inside the incubatory sac. There may, however, 

 possibly be in those cases a condensed embryology, as I have 

 myself shown in the most different groups, and, for example, 

 in the Tunicata. Anyhow the embryo of Suctoria never 

 acquires a higher form than this Cypris stage, which in no 

 wise resembles the figures drawn by F. Miiller ; and it is 

 from this moment that the retrogressive metamorphosis begins. 



I am, Gentlemen, 



Yours obediently, 



Lille, August 2, 1878. ALFRED GlARD. 



* Oomptes Rendus de I'Academie des Sciences, t. Ixxvii. 1873, p. 949; 

 C. R. t. Ixxix. 6 et 27 juiUet 1874; Annals and Magazine of Natural 

 History, ser. 4, vol. xiv. pp. 381 and 386. 



