1372 



CRUSTACEA. 



Genus LEPIDOPTJS, Dana. 



Corpus antich no?i latins. Cephalotliorax 3-articulatus, segmentis 2dis 

 Stiisque postich large bi-alatis. Abdomen 2-articulatum, segmento 

 postico parvulo, celato, antico maximo et posticd bilobato. Antenna 

 postico3 articulo tenui falciformi confectai, marginibus bene denticulatce. 

 Pedes paris secundi snperficie lata terminali pre7ie?isili squamatd in- 

 structi. Pedes natatorii quatuor ultimi similes, lath lamellati, \mi 

 simplicissimi, setis totis perbrevibus. 



Body not broadest anteriorly. Cephalo thorax three-jointed, second 

 and third segments posteriorly large bi-alate. Abdomen two-jointed, 

 the last segment quite small and concealed below, the other very 

 large and bilobate behind. Posterior antennae ending in a slender 

 falciform joint, having the margins neatly denticulate. Prehensile 

 feet of second pair having the last joint broad and flat below, and 

 covered with scales for adhesion. Last four natatory feet similar, 

 broad lamellar, first pair quite simple, setae all very short. 



This genus is near Laemargus, but differs in having the second seg- 

 ment two-winged like the third, and the large prehensile legs end in 

 a broad disk, for attachment and locomotion. The posterior antennas 

 in the only species seen terminates in a long curved joint, which is set 

 with two rows of minute teeth. The first and second pairs of nata- 

 tories are nearly as in Pandarus, except that the first is without a 

 second branch. The third and fourth have the basal joint enlarged 

 and flattened into a nearly circular lamina, with the two branches 

 mere one-jointed appendages to the posterior edge. 



The first pair of feet are furcate at apex, as in other Caligidae; this 

 furcation arising, as usual, from the prolongation of the second joint, 

 and the addition, where this prolongation begins, of another slender 

 joint of similar character. 



The buccal trunk is long and slender, and the mandibles have a 

 straight extremity, with the inner margin serrulate. The maxilla? 

 are close appressed to it near its base. 



The last segment of the body is concealed below, and terminates in 

 two small processes, corresponding to stylets. The frontal segment of 

 the carapax is separated by a suture, and is longer than usual. 



