ZOOLOGY. 
CCXXXl 
is a third species, differing not merely in appearance, but in its habits, being 
found only in fresh water. The Oniscus Pulex of Otho Fabricius, Faun. 
Green., No. 231, differs from the present species in the relative proportions 
of the . three posterior pair of legs, the last pair being described by Fabricius 
as less than the two preceding, whereas in the Boreus the seventh are longer 
than the fifth and sixth pairs. The Oniscus Cancellus of Pallas, Spicil. 
Zool. ix. p. 53, tab. 3, f. 18, is distinguished by the lateral scales on the seg- 
ments of the body, but in other respects is not very dissimilar to the animal 
under description : it may not be amiss to notice incidentally that an error 
has crept into the specific character of the Cancellus in the writings of modern 
authors, commencing it is believed with J. C. Fabricius, of describing it 
with sixteen legs, instead of fourteen, which is the usual number in the 
genus; in the original account of the Cancellus, Spicil. Zool.l.c. the number 
of legs is fourteen, both in the description and figure. 
Gammarus Lorictaus. 
G. Rostro corniformi deflexo, dorso carinato, segmentis postice et acute productis. 
Plate 1. fig, 7. 
This species was found associated with the preceding, and of the same 
size, but less abundant ; body laterally compressed, especially the posterior 
segments ; shell smooth, and much harder than in its congeners, resembling 
a coat of mail, whence the specific name ; back carinate, the segments in- 
creasing in length from the first to the tenth, from whence they decrease ; 
and beginning with the third or fourth, are produced in sharp and strong 
points directed backward ; lateral lobes oblong, enlarging from the first to 
the fourth segment, and decreasing to the seventh ; those of the three first 
caudal segments are larger than those of the body, and are acuminate ; head 
produced into a strong, arched, carinate, and sharp-pointed rostrum, curving 
down between the antennae ; eyes large, black, lateral, prominent and reni- 
form ; beneath the eyes is a small lateral lobe ; antennae four-articulate, the 
