REPORT ON THE CRUSTACEA MACRURA. 797 



The mandibles are like those of Pcdasrnon, and appear not to differ specifically from 

 those of Palsemon serratus ; the psalistoma is broader at the base than at the extremity, 

 the molar process is angular and well developed, and the synaphipod is very slender, 

 three-jointed, and not longer than the psalistoma. 



The oral appendages closely resemble those of Palsemon, exhibiting no conspicuous 

 variation. 



The gnathopoda also correspond with those of Palsemon serratus, excepting that the 

 second pair has the extremity terminating in a long and sharp-pointed unguis, and the 

 appendage is more thickly fringed with hairs in numerous fasciculi. 



The first pair of pereiopoda is long, slender, and chelate, and formed on the same type 

 as that of Palsemon serratus ; the coxa is produced on the inner side and supports a brush 

 of hairs ; the basis and ischium are both short, the latter being narrower at the basisal 

 articulation than at the meral ; the meros and carpos are long and subecpial ; the 

 propodos is shorter than the carpos, the palm being subecpial with the dactylos ; the 

 dactylos and pollex are parallel, impinging throughout their entire length, and having 

 their extremities rounded on the outer margins. This pair of appendages corresponds 

 with that of the typical Palsemon. The second pair of pereiopoda is very long and very 

 large ; it has the carpos short, the propodos long and cylindrical, the palm about twice 

 the length of the pollex, and the pollex slightly curved and furnished on the inner 

 margin with two strong, obtusely pointed teeth or tubercles ; the dactylos is also 

 curved, and a trifle longer than the pollex, and each of these joints terminates in a 

 sharp, strong, opposing unguis, and has the inner margin broad and fringed with a 

 closely packed row of strong but short hairs, so that when the chela is closed the inter- 

 vening space is filled with a brush of hairs. The three posterior pairs of pereiopoda are 

 robust and not very long ; the meros is longer than the ischium, and the carpos is one- 

 third shorter than the meros and overlaps the propodal articulation on the anterior 

 surface ; the propodos is a third longer than the carpos, and furnished with two or three 

 solitary spinules on the posterior margin ; the dactylos is short, curved, and terminates 

 in a curved, bifid unguis, both points being sharp. 



The pleopoda are foliaceous, biramose, and have the basal joint broad and flat. 



The rhipidura has the outer plate furnished with a short tooth, and a longer spine at 

 the outer extremity of the diaeresis, the inner plate is subequal with the outer, and both 

 longer than the telson. 



The telson is broad at the base, narrow and pointed at the extremity, and has the 

 dorsal surface flattened ; the dorsolateral angle on each side is armed with two solitary, 

 short, stout spines, one behind the other, and the posterior angle on each side with a 

 short spine, immediately to the inner side of which is a second spine about one-eighth 

 the length of the telson ; between these spines on the under surface the margin is 

 fringed with hairs subequal with the larger spines. 



