174 ANCEUXE. 



In 1858, Mr. 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 " etat 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 1'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 Pranizes 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." 



