MEMOIRS OF TOE NATIONAL ACADEMY OF SCIENCES. 349 



rostrum also bears oil each side a single row of about four teeth projecting forward. The under 

 side is unarmed. Several large spines occur in the angle behind the eye and on the basal joints of 

 the antennae. 



The epidermic spines, which are characteristic of the Hispidus, though not confined to this 

 species, are found upon the dorsal surface of the entire body, on the third pair of pereiopods and 

 on the bases of the appendages generally. The first, second, fourth, and fifth pairs of thoracic 

 legs are destitute of conspicuous spines. The spines of the carapace and anterior abdominal terga 

 are bent forward; those of the fourth, liftli, and sixth abdominal somites and of the tail tin are 

 oppressed, stouter, uondentiiate, and point backwards. 



The telson is arrowhead-shaped; its free edges are garnished with short, closely set hairs; it 

 has a median groove, bordered on either side by a longitudinal elevated ridge, bearing spines; it 

 hardly surpasses the uropodal lamellae. The eyes project at right angles to the long axis of the 

 body. They have dark brownish black pigment and are mounted upon short, stout stalks, covered 

 with small prickles. The labrum consists of a semicircular bar, the convex surface ot which points 

 forward and bears two nearly median spines projecting downward. From its concave border is 

 suspended a Ungulate appendage, which is supported by a thin, median, and vertical plate. The 

 inner antenna; (Fig. 40) bear very long flagella, the disposition of which has already been noticed 

 (Sec. i). The segments of the stalk are armed with stout denticles, and each division of the 

 proximal portion of the outer tiagellum or exopodite bears externally a sharp spine. 



The outer antenna) (Fig. 41) possess at their base a long, narrow scale (exopodite), "which is 

 traversed by longitudinal grooves. Their inner borders, which meet in the middle line, are fringed 

 with closely set hairs. The stalk or protopodite is spiny, and the flagellum or endopodite is two 

 and a half times the length of the body of the animal. The mandibles (Fig. 39) bear very large 

 palpi, and have blunt interlocking teeth ; a transverse furrow divides the cutting surfaces of ea.ch. 

 The first pair of maxilhe (Fig. 38) consist of an inner (coxopodite) and outer branch (basipodite), 

 with a slender endopodite. The outer division or coxopodite is thickly beset with strong spines. 

 The second pair of maxilla? (Fig. 42) are furnished with an elongated plate, the "bailer" or 

 scaphoguathite, which is fringed with hairs, an inner lobulated portion (basipoditeaud coxopo- 

 dite), and an intermediate eudopodite, which bears several plumose hairs at its distal end. 



The first pair of maxillipeds (Fig. 43) consist of an inner lobulated portion (coxopodite and 

 basipodite), thickly studded with short bristles, an outer triangular plate (epipodite), and two 

 intermediate appendages. The innermost of the latter (eudopodite) terminates in a stout spine. 

 It consists of two segments armed without by a row of long plumose hairs. The whip-like, 

 appendage exopodite next this is twice as long and is bordered with short hairs. In the second 

 pair of maxillipeds the basil portion consists of several lobules, tufted with hairs, and a small, 

 external epipodite. There is a stout incurved eudopodite, with hirsute terminal joints, and a Jong 

 slender exopodite. A transparent lamella springs from the outer side of the proximal half of the 

 the eudopodite, and bears plumose hairs on its free margin. 



The third pair of maxillipeds (Fig. 46) are long and conspicuous, somewhat less slender 

 than the first or second pairs of thoracic legs. The inner and outer borders are fringed with 

 long hairs. The outer border is denticulated ; the distal extremities of the segments, as of the 

 ischiopodite, produced into a sharp spine. The basipodite is small, bearing the persistent and rudi- 

 mentary exopodite, which is a slender palp equal in length to the ischiopodite. The first pair of 

 dereiopods (Fig. 47) are small, slender, and chelate. The second pair of pereiopods are similar to 

 the first pair, but longer. 



The third pair of pereiopods, the " great chela;," differ somewhat in size, the right being some- 

 times larger and sometimes smaller than the left. The chela is compressed and slightly twisted. 

 There is a single row of stout regular denticles, forming a saw-tooth edge on either margin of the 

 " palm," and several rows of lesser spines on the broad sides. There is also a longitudinal groove 

 extending to the base of the dactyle. The carpus is prismatic and bears about five rows of large 

 teeth. The ischium is more cylindrical, but similar. The dactyle and propodns possess each a 

 prominent tooth, which fits into a corresponding depression. 



