174 ANCEIDiE. 



In 1858, Ml*. Spence Bate communicated a memoir 

 " on Praniza and Anceus, and their Affinity to each 

 other/' in the " Annals of Natural History," 3 ser. vol. ii. 

 pi. 6 and 7, in which, after a careful description of the 

 structure of the two, Anceus and Praniza, and a review of 

 the statements of previous writers, and especially of the 

 memoir of M. Hesse, he arrived at these conclu- 

 sions : — 



1. That (upon M. Hesse's observation of Anceus pro- 

 ducing young) Anceus is an adult animal. 



2. That (upon his own observation of Praniza pro- 

 ducing young) Praniza is an adult animal. 



3. That Praniza, consequently, cannot be developed 

 into Anceus. 



4. That Anceus is a distinct genus from Praniza. 



5. That the males of both genera have yet to be dis- 

 covered. 



In 1861, M. Van Beneden, in his " Recherches sur la 

 Faune littorale de Belgique, Crustaces," published a de- 

 tailed description, with figures, of the Oniscus {Praniza) 

 marinus, of Slabber, as the " ^tat larvaire," and of the 

 Anceus as the " etat adulte " of the same animal, pre- 

 ceded by a history of the genus, and of the observations 

 of Messieurs Hesse and Spence Bate, together with a 

 supplemental note from the former to the objections of 

 the latter : — 



" Si vous prenez des Pranizes d'une certaine dimen- 

 sion, c'est-a-dire, pres de I'epoque de leur transforma- 

 tion, vous n'avez plus, au bout de quelques jours, des 

 Pranizes mais des Ancees des deux sexes — quelques jours 

 avant la transformation des Pi'anizes femelles en Ancees 

 les ceufs qui preexistent s'apercoivent a travers la peau, et 

 si M. Bate avait vu la suite de cette operation, il eut 

 constate que sa Pranize etait devenue Ancee.^' 



