172 ANCEIDZ. 
municate a memoir on the subject to the meeting of the 
British Association at Oxford, in 1832 ;—a translation of 
which, with additions, containing the description of some 
supposed new species of Praniza, was published in the 
“ Annales des Sciences Naturelles.” Other supposed 
species of the two sexes of this genus were published 
by other authors, namely, Praniza branchialis, of Otto 
(in “ Nova Acta” of Bonn, vol. xiv.) ; Praniza ven- 
tricosa, plumosa, and mesosoma, of Risso (‘ Hist. Nat. 
Eur. Merid.” vol. v.); Praniza Reinhardi, of Kroyer 
(‘‘ Gronlands Amfipoder’”’); Anceus rapaz, of Milne Ed- 
wards (“‘ Hist. Nat. Crust.” vol. iii.); Anceus vorax, of 
Lucas (“Annales Soc. Ent. France,” 1849); Praniza 
mauritanica, of Lucas (“‘ Op. Cit.”); and Praniza obesa, of 
Lucas (“ Op. Cit.” and “ Hist. Nat. Alger,” tome i.). 
Whilst establishing the genera Gnathia and Praniza for 
the two sexes of this genus, Dr. Leach had the tact to 
perceive the possibility of their being sexes of one and 
the same species, observing (‘‘ Edin. Encyc.” vii. p. 402) 
that “ Mr. Leach supposes that Oniscus ceruleatus, of 
Montagu, is the female of this animal” (Gnathia termi- 
toides, or mazillaris, Mont.). Hence possibly the reason 
why Dr. Leach did not introduce his MS. genus Praniza 
into any of his works; indeed, he omitted Gnathia in 
his celebrated memoir published in the “ Transactions 
of the Linnean Society,” vol. xi. 1815. 
In November, 1855, M. Hesse communicated a me- 
moir to the Académie des Sciences, of Paris,* in which 
he announced the startling fact that Praniza was but the 
larva state of Anceus, and that, by a true metamorphosis, 
Praniza was transformed into Anceus. 
In the beginning of the following year, 1856, our 
* Comptes rendus, Noy. 1855, March 1858. Ann. des Sci. Nat. 1858, 
t. ix. p. 89. 
