CCXXXIV 
APPENDIX. 
means remarkable either in this species, or in some others, which are dis- 
tributed by it into the respective genera of Talitrus and Gammarus ; if a sub- 
division be desirable in 'the well-defined and natural genus comprehending 
all these animals which so nearly resemble each other in general appearance 
and habits, the prolongation of the anterior part of the head into a rostrum, 
would seem preferable to a distinction founded on the relative length of the 
antennae, which in many of the species are so nearly the same ; or, the 
genus Talitrus might be limited to those species in which the superior 
antennae are very short, not exceeding the length of the two first articula- 
tions of the inferior pair. 
This species has been named in compliment to John Edwards, Esq., surgeon 
of the Hecla. 
Talitrus Cyaneas. 
T. capite obtusissimo, antennis subsequalibus, corpore latiore, pedibus quatuor anticis inunguiculatis. 
Plate 1, fig. 12 — 18. 
Parasitic on the Cyanea Arctica, the individuals varying in length from two 
to eight-tenths of an inch : colour pale yellowish red, sprinkled with innu- 
merable minute spots of deeper red; in about half the specimens, the 
number of which was considerable, the antennas were equal in length to the 
five first segments of the body ; in the others they were scarcely one- 
fifth as long, but otherwise similar ; there was no other perceptible differ- 
ence in the specimens. The two pair of antennae are so very nearly 
of the same length, that it has been by no means easy to decide whether 
the species should be considered a Gammarus or a Talitrus; those of an 
individual, however, in which the greatest disproportion existed, have been 
figured (fig. 14, 15, and 16,) for the purpose ofjustifying the ultimate decision ; 
the remarkable conformation of the head will doubtless be considered by 
many naturalists as a peculiarity requiring the establishment of a new genus. 
Head rounded, and very obtuse ; eyes extremely large, lunate, of a brownish 
