LiEMODlPODA. 97 



ticulated 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 composed of eight or nine seg- 

 ments, including the head, and some small appendages in the 

 form of tubercles at its posterior and inferior extremity. The 

 feet are terminated by a stout hook. The four anterior, the 

 second of which are the largest, are always terminated by a 

 monodactyle forceps or a claw. In several, the four follow- 

 ing ones are shortened, less articulated, without the terminal 

 hook, or are rudimental, 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. Savigni considers 

 them as allied to the Pycnogonides, and constituting with the 

 latter the transition from the Crustacea to the Arachnides. 

 In the first edition of this work they formed the first section 

 of the Isopoda, that of the Cistibranchiata. 



We may unite them in a single genus which, by the law of 

 priority, should be called the 



Cyamus, Lat. 



Some — the Filiforma, Lat. — have a long and very slendei* or 

 linear body with longitudinal segments; feet equally slender and 

 elongated, and the stem of the antennse 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 up their body, during which time the antennae are vibrating. 

 While swimming, the extremities of their body are curved. 



Leptomera, Lat. — Proto, Leach. 



Fourteen feet, including the two annexed to the head, all complete 

 and in a continuous series. 



Here, as in our Leptomera proper — Gammarus pedatus, Mull., 

 Zool. Dan., CI, 1, 2 — all the feet, the two anterior excepted, have a 

 vesicular body at their base. 



There, as in the Proto, Leach — Cancer pcdatus, Montag., Trans. 

 Vol. IIL— N 



