MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 349 



rostrum also bears on 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 Ilispidus, tliough not confineil to this 

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

 on the bases of the appendages generally. The first, second, fourth, and liftli iiairs of thoracic 

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

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

 ai>pressed, stouter, nondentilate, and ])oint backwards. 



The telsou 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 of which points 

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

 suspended a liugulate ai)i)endage, which is supported by a thin, median, and vertical plate. The 

 inner antennsc (Fig. 40) bear very long tiagella, 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 jtortiou of the outer Uagellum or exopodite bears externally a sharp spine. 



The outer antennw (Fig. 41) possess at their base a long, narrow scale (exoi)odite), 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 sj^iny, and the tlagellum or eudopodite 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 each. 

 The first pair of maxilhe (Fig. 3S) consist of an inner (coxojwdite) and outer branch (basipodite), 

 with a slender eudopodite. The outer division or coxopodite is thickly beset with strong sjiiiies. 

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

 scaphognathite, which is fringed with hairs, an iwuer lobulated portion (basii)oditeand coxoi>o- 

 dite), and i^n 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 a})pendages. The innermost of the latter (eudopodite) terminates in a stout spine. 

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

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

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

 external ei)ipodite. There is a stout incurved eudojjodite, with hirsute terminal joints, and a long 

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

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



The third pair of maxillipeds (Fig. 4G) are long and conspicuous, somewhat less slem'er 

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

 long hails. 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 rmli- 

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

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

 the first pair, but longer. 



The third pair of pereiopods, the "great chehe," 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 propodus i)ossess each a 

 prominent tooth, which fits into a corresponding depression. 



