CRUSTACEA. 
289 
promincntibus, oculos ferentibus. Gnathopoda et pereiopoda omnia ambu- 
latoria, longitudine sensim crescentia. Fleon ex segmentis 6 compositum. 
Pleopoda anteriorum 4 biramea^ setigera; pleopoda posterioris paris brevis- 
sima, simplicia, esetia. Telsmi nullum. 
Icridium fuscum^ Grube (taf. 4. f. 3). There is a slight discrepancy between 
Prof. Grube’s excellent figures and the description. First, the telson is un- 
doubtedly present ; and since the ante- and penultimate pairs of pleopoda are 
attached to one somite, we must rather consider that the two somites are fused 
into one than that one is wanting. We therefore perceive that one, instead 
of two somites, only is wanting j but it is contrary to previous observation that 
this deterioration takes place in the anterior portion of the pleon instead 
of the posterior ; for undoubtedly one of tile anterior pairs of pleopoda is the 
missing pair. Prof. Grube considers this genus very near to Icilius, Dana. 
Cm'apus latimanusj sp. n., Grube, Insel Lussin, p. 74, from Neresine. 
Caprellid^e. 
Caprella kennerlyij sp. n., Stimpson, Proc. Ac. Nat. Sc. Phil. 1864, p. 166, 
from Port Townsend. — Caprella mermis, sp. n., Grube, Insel Lussin, p. 76, 
from Lussin piccolo. 
ISOPODA. 
Tanaid^. 
Dr. Fritz Muller (Arcliiv fiir Naturg. Band i. p. 1), in de- 
scribing the structure of the genus Tanais, asserts that the cepha- 
lon is developed upon the type of the carapace of the Decapoda, 
that although he has not been enabled to define branchial ap- 
pendages, yet, since he has observed that a current of water 
flows anteriorly under the lateral walls as in the higher orders, 
it undoubtedly fulfils the same office, though probably in a less 
perfect manner than is the case even in the Diastylidse where 
rudimentary organs exist. He also describes the internal ana- 
tomy as well as the ovisac and external organs of sense. We 
regret that the limits both of time and space afforded to us 
preclude our doing justice to the contents of this very inter- 
esting communication ; but we are compelled to say that our 
carefully made researches disagree with those of Dr. Muller, 
and that if any current passes anteriorly, as observed by 
him, it must pass externally to the lateral walls of the cara- 
pace, and not within them. For, in consequence of the large 
development of the anterior pair of gnathopoda, the lateral 
walls of the carapace are compressed to so great a degree as 
to shut out all communication between the posterior and an- 
terior surfaces ; independently of which, the branchiae (being 
appendages of the pereion) can only exist beneath the carapace 
where the cephalon is developed to so great an extent as to cover 
the appendages of the pereion. 
Prof. Lilljeborg, who has done such good service to the study 
of carcinology, has furnished us with a memoir which is entitled 
A Contribution to the knowledge of the Suborder Isopoda of 
1864. [voL. I.] u 
