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e From the American Journal of Science and Arts, 2nd Series, Vol. XIIT.—Jan., 1852. 
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"t CLASSIFICATION , 
EU OF THE 
CORYSTOIDEA, PAGURIDEA, E'P€ 
By JAMES D. DANA. T LUA 
u 
l. THE ConvsTorpEA have their closest relations with the Can- 
croidea, and form a passage between this division of the Brachyura and 
. the Hippidea. "They are remote from the Oxystomata in the mouth 
and efferent branchial channels, the latter having these channels medial 
over the palate, and the former lateral like the Cancroids. . In the pro- 
.. jection of the outer maxillipeds over the epistome, the elongated and 
- more or less pilose outer antenuze, and the partially free or less closely 
inflexed abdomen, the species exhibit their degradation below the Can- 
cer dype. The Platyonychidz are the Cancroids which approximate 
-— most to the Corystoids, and they are placed with this group by De. 
- Haan. But they differ from the Corystoidea in the shorter and more 
—— paked outer antenng ; ; and we therefore incline rather to retain them 
1 with the Crancroidea, where they are arranged by Milne Edwards. 
'The degradation of the Cancroidea is also seen in anotlier line lead- 
ing through Acanthocyclus to Corystoides, Lueas, and Bellia, Edw.* 
The last two genera are somewhat Corystoid in habit: yet they pertain 
to a distinet group, inasmuch as they have the outer antennz: obsolete 
or nearly : so, and the inner antennz without fossetles. "'Phis last char- 
acter belongs only to the lower Anomoura and the Macroura, and places 
ihese genera quite low in rank in a group we name BELLIDEA which 
belongs near if not among the Anomoura. 
In attempting to arrange the Corystoidea into groups, we consider, 
as in other cases, the relations of the species to the higher Crustacea, — 
and by the transitions observed, we are led to our subdivisions.  Tri- 
chocera is Cancroid in habit, in the absence of a beak, in the nearly 
. naked outer antenne, and in having the outer maxillipeds fitted neatly 
..to the epistome. — Thia and Kraussia are also without a beak, like the 
Cancroids, but have the outer maxillipeds overlapping the epistome. 
'The remaining genera have the front somewhat rostrate, the inner an- 
* tenne longitudinal, the maxillipeds produced over the epistome and 
. the outer antennze elongate and pilose and flexed at base towards the - 
medial line. 'T'he form of the third joint of the outer maxillipeds varies 
from narrow oblong to transverse in closely related Benalsi and affords 
^. no basis for a family distinction. - 
4 
" * In the synopsis of the Cancroidea in this Jour., vol. xii, p. 131, Corystoides was: 
^. placed near Acanthocyclus, to which it has close relations; but from this and the 
— other Caneroids, it is removed by the absence of all power of retraction in the 
E inner antenna. 
k The name Bellia has been recently duplicated in the science, in an article by Mr. 
C. Spenee Bate, on a new genus of Ampbipods near Lepidacty lis, published in the 
Annals and Mag. Nat. Hist., [2], vii, 318, pl. 11, f. 8, 1881. The description of Milne 
Edwards's genus of tliis name is published in the Ann, des Sci, Nat. [3], ix, 1848, 
p. 192. 
Sucoxp SxRIES, Vol. XIII, No, 31.—Jan., 1852 N 15 
