IDOTEA PARALLELA. 393 
agree entirely with Costa’s description and figure of 
Id. chelipes in form and structure, as well as with another 
specimen in the same collection labelled by Signor Costa 
himself. 
It is evident, however, that the C. chelipes of Fabricius 
and Latreille cannot be identified with the animal before 
us, the ‘‘ Cauda” tridentata of the Fabrician description 
being entirely distinct from the remarkable character of 
the extremity of the tail of I. parallela. Signor Costa 
states of his species, ‘‘ Trovasi ne’ mari d’Inghilterra e di 
Zelandia,” taking the habitat from Pallas by regarding 
his species as the Oniscus linearis of Pallas’ ‘‘ Spic. Zool.” 
fasc. 9, t. 4, f. 17 and 18. These figures are indeed bad, 
but there can be little doubt that they represent small 
and narrow specimens of J. tricuspidata, and we believe 
Fabricius was correct in referring Pallas’ figures to his 
C. chelipes, as Pallas describes the tail of his species as 
obscurely tridentate, and indeed refers his linearis to 
O. chelipes of his former work, from which probably Fabri- 
cius had taken it up. 
