PROTO. o7 
other, while the seventh pair are much nearer the sixth. 
The fifth pair of legs are the shortest, the fourth pair 
being longer, and the third still a little longer. The last 
two pairs of legs are long and powerful. The branchiz 
are attached to the second, third, and fourth pairs of 
legs. The tail is rudimentary, and the appendages at- 
tached to it almost obsolete. 
The geographical range of this genus is, as yet, 
limited to the British seas and the adjacent coast, with 
the exception of a single specimen taken by Dana on the 
south-eastern shores of South America. 
Latreille appears to have made much confusion respect- 
ing the nomenclature of the present group by attempting, 
in his different works,* to distinguish his genus Leptomera 
from that of Proto of Leach, proposing also a third 
generic name Naupredia (Naupridia, Milne Edwards), for 
an animal described as having only ten legs in a con- 
tinuous series, those of the second, third, and fourth 
pairs having a vesicle at the base, and which is evidently 
a Proto with the sixth and seventh pairs of legs acci- 
dentally broken off. He has evidently, also, fallen into 
error in giving the Gammarus pedatus of Montagu and 
of Miller and the Squilla ventricosa of Miller as three 
distinct species, referable to separate sections or sub- 
genera. 
* Régne Animal, 1st edit. iii. p. 51; 2nd edit. iv. pp. 127, 128. Nouv. 
Dict. @Hist. Nat. 2nd edit. p. 483 (Art. Chevrolle) ; xvii. p. 485 (Art. 
Leptomere) ; xxviii. p. 177 (Art. Proton). 
+ Van Beneden (Recherches sur la Faune litt. de Belgique, Crust. 1861, 
p. 97, pl. xvii.) has described a species which he names Naupredia tristis, 
asserting that it is a perfect animal, and not a mutilated Proto (Leptomera). 
It is only five millemetres long, and is most probably in a very young state. 
It entirely agrees with Proto, except in the inarticulated flagellum of the 
antenne and want of the four hind legs. It is possible that these may 
be subsequently developed ? 
