L.EM0D1P0DA. 
225 
They all have four setaceous antennas supported by a tri-articulated 
peduncle, mandibles, without palpi, a vesicular body at the base of at 
least the four pairs of feet, beginning at the second or third pair, those 
of the head included. The body, usually filiform or linear, is com- 
posed of eight or nine segments, including the head, and some small 
appendages in the foi’in of tubercles at its posterior and inferior ex- 
tremity. The feet are terminated by a stout hook. The four anterior 
the second of which are the largest, are always terminated by a mo- 
nodactyle forceps or a claw. In several, the four following ones are 
shortened, less articulated, without the terminal hook, or are rudi- 
mental, and nowise adapted for the ordinary uses of similar parts. 
The females carry their ova under the second and third segments 
of the body in a pouch formed of approximated scales. 
They are all marine Crustacea. M. Savigny considers them as 
allied to the Pycnogonides, and constituting with the latter the tran- 
sition from the Crustacea to the Arachnides. In the first edition of 
this work they formed the first section of the Isopoda, that of the Cis- 
tibranchiata. 
We may unite them in a single genus which, by the law of priority 
should be called the 
C YAM us, Lat . 
Some — the Fiu forma, Lat. — have a long and very slender or 
linear body avith longitudinal segments ; feet equally slender and 
elongated, and tlie stem of the antennee composed of several small 
joints. 
They are found among marine plants, walk like the caterpillar 
termed the Geometra, sometimes rapidly revolving in a circle, or 
turning \ip their body, during which time the antennse are vibrating. 
Wliile swimming, the extremities of their body are curved. 
Lei’tomera, Lat. — Proto, Leach. 
Fourteen feet, including the two annexed to the head, all complete 
and in a continuous scries. 
Here, as in our Levtomeiia proper — G ammarm pedalm., Mull., 
Zook Dan., Cl, 1, 2 — all the feet, the two anterior excepted, have a 
vesicular body at their base. 
There, as in the Proto, Leach — Cancer pedatu^;. Montag., Trans. 
Lin. Soc., II, 0; Encyclop. Method., Atl. d’Hist. Nat. CCCXXXVI, 
38 — those appendages arc only i)roper to the second, and four fol- 
lowing feet *. 
* We should also refer to the Leptomerse, the Squilla ventricosa, Miill., Zool. 
Dan., LVI, 1 — ; Herbst., XXXVI, ii : — the Cancer linearis, L., is perhaps a con- 
gener. He describes it as having six feet, but does not include the head. 
VOL, III. q 
