170 Mr. C. Spence Bate on the Affinity of Praniza with Anceus. 



The experience of M. Hesse is quite at variance with my own 

 observations. The larva which I have figured in PL VI. fig. 2 is 

 one of about twenty that I obtained from the Praniza I have 

 given in fig. 1. It appears therefore that some fallacy must 

 have crept into the researches of M. Hesse, since Praniza is 

 evidently an adult animal. The mysterious law governing repro- 

 duction under the phase of alternation of generations can scarcely 

 account for the discrepancy, since the young of Praniza bear to 

 the parent as close a resemblance as is found usually to exist 

 between the old and young. They differ only in the relative 

 proportion of certain parts ; and others, which are not required 

 until the age of puberty, are necessarily in abeyance. 



M. Hesse says that Anceus bears young. This fact being dis- 

 covered by him, proves that there are female Ancei. This, to- 

 gether with the fact that I have stated relative to Praniza, 

 demonstrates the error of M. Hesse's hypothesis, " that Praniza 

 is the early stage of Anceus" and goes far to establish the fore- 

 gone conclusions of previous naturalists, that the two animals 

 belong to distinct genera. 



M. Hesse says not only that Anceus bears young, but that 

 these young are Pranizce. We know, from experience in obser- 

 vation, that the larva? of any given tribe of Crustacea are gene- 

 rically similar : as I have previously shown, there is a considerable 

 resemblance between the young of Praniza and the adult Anceus ; 

 so therefore we may infer that the general resemblance of the 

 larva of Anceus to the larva of Praniza is considerable, — a cir- 

 cumstance that may account for M. Hesse's assumption that 

 the former are Pranizce. 



I think we may, from what is known, deduce the following 

 conclusions : — 



That (upon M. Hesse's observation) Anceus is an adult animal. 



That (upon our own observation) Praniza is an adult animal. 



That Praniza consequently cannot be developed into Anceus. 



That Anceus is a distinct genus from Praniza. 



That the males of both genera have yet to be discovered. 



The males of both Anceus and Praniza have to be made out ; 

 but it is not rash to infer that they may so nearly resemble the 

 females, as to make it a test of considerable difficulty. 



I have recorded that in Praniza Edwardsii the gnathopoda 

 have an immature character, while in P. cceruleata they possess 

 the appearance of an efficient organ. It is not improbable that 

 this may be a sexual distinction in every species of Praniza : to 

 this inference I am led by the fact that all the larva? of Pra- 

 niza Edwardsii possess the powerful hook seen in P. cceruleata, 

 while it is absent in the parent. I have elsewhere expressed 

 a conviction that the larva? of Crustacea possess at an early 



