646 TETRADECAPODA. 



to the present order. We folbw Prof. Dana in placing here 

 (1) the WOOD-LICE, Oniscida, (Gr. oniskos. a wood-louse,) 

 sometimes referred to the order Isopoda, (Gr. equal-footed.) 

 These have fourteen slender feet, adapted to walking, and the 

 first pair of antennae rudimentary ; the second pair being alone 

 complete and conspicuous. The species Oniscus asellus, (Lat. 

 a chee-slip or sow-insect,) (Plate XVI. fig. 2a,) is the COMMON 

 SOW-BUG, found under stones and decaying wood. The fourteen 

 feet gradually increase in size from the front; the antennae have 

 eight articulations. The Sow-bug feeds upon decomposed veg- 

 etables. It carries its eggs in a sac beneath the body. The 

 color is dusky brown above ; beneath greyish white. The Porcel- 

 lio, (Lat. a sow-bug or wood-louse,) spinicornis, (Lat. spiny horns,) 

 is very similar to the Oniscus, but its antennse have only seven 

 articulations. The third joint of the antennse is armed with an 

 acute spine. This also has the popular name of Sow- hug, and 

 is found in similar situations with the preceding. The species 

 P. granulatus, (Lat. granulated,) or Hog-louse, is black and un- 

 spotted. . It is roughened with small elevated grains, whence 

 the specific name. 



To the Sow. bugs are similar, in most respects, those of the 

 genus Armadillo, which, from their habit of rolling themselves 

 into a ball, are known by the name of PILL-BUGS. These are of 

 dull lead color, with three lines of large yellowish spots on the 

 upper part. 



The WHALE-LOUSE, Cyamus ceti, (see Chart,) referred by La- 

 treille to the order L^EMODIPODA, (Gr. throat or jaw-footed,) the 

 Oniscus ceti, of Linn., has at least twelve feet, of which eight 

 are perfect, and the others in the form of slender, jointed append- 

 ages. It attaches itself to whales, and occasionally to tunnies 

 and other large fish. 



(2) The SAND, or BEACH FLEAS, Gammarida, sometimes re- 

 ferred to the order AMPHIPODA, (so named from having two kinds 

 of feet, cheliform or claw-like, and simple.) The family in- 

 cludes several genera and species. Orchestria, (from Gr. 

 orchevomai, to leap,) longicornis, (Lat. long horned,) is a species 

 having the lower antennas longer than the body, and the four 

 front feet terminated in a compressed claw. They subsist upon 

 dead animal substances. They are found on the shores of Long 

 Island, where, to conceal themselves, they dig holes in the sand. 

 Other Sand or Beach Fleas are included in the genus Talitrus. 

 Of this is the species T. quadrijidus, (Lat. four-cleft,) which 

 have a body composed of thirteen segments, exclusive of the 

 head ; and the antennse shorter than the body. The tail has 



