174 ANCEIDA. 
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. 11. 
pl. 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, Crustacés,” published a de- 
tailed description, with figures, of the Oniscus (Praniza) 
marinus, of Slabber, as the ‘* état larvaire,”’ and of the 
Anceus as the “état 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, prés de l’époque de leur transforma- 
tion, vous n’avez plus, au bout de quelques jours, des 
Pranizes mais des Ancées des deux sexes—quelques jours 
avant la transformation des Pranizes femelles en Ancées 
les ceufs qui préexistent s’apercoivent a travers la peau, et 
si M. Bate avait vu la suite de cette operation, il eut 
constaté que sa Pranize était devenue Ancée.”’ 
