172 ANCEID^l. 



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. Mend." vol. v.) ; Praniza Reinhardi, of Kroyer 

 (" Gronlands Amfipoder "); Anceus rapax, 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 cceruleatus, of 

 Montagu, is the female of this animal " (Gnathia termi- 

 toides, or maxillaris, 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 Academic 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, Nov. 1855, March 1858. Ann. des Sci. Nat. 1858, 

 t. ix. p. 89. 



