REPORT ON THE CRUSTACEA MAi KI'llA. L»l 



and propodos are short and form a rigid curve, and terminate in a short flat spatuliform 

 dactylos that is distally fringed with stiff spines. The coxa supports an imperfect or 

 rudimentary forked mastigobranchia, tipped with long hairs, and a podobranchial 

 plume made up of trichobranehial filaments and phyllobranchial plates longitudinally 

 implanted on the stem. The basis carries an ecphysis that is as long as the gnathopod. 



The second pair of gnathopoda has seven joints, the meros and ischium being dis- 

 tinct and continuous ; both, but more especially the ischium, arc longitudinally grooved 

 or excavated, forming a hollow in which lies closely impacted, when at rest, the first long- 

 joint of the basecphysis; the carpos is long and curved, the propodos straight, and the 

 dactylos long and straight, fringed on both the upper and under margins with long hairs, 

 as also on the under or inner side of the propodos, ischium, and meros. The basecphysis 

 is about two-thirds the length of the gnathopod, and is fringed with long hairs. The coxa 

 supports a short, slightly curved, rigid mastigobranchia, fringed on the lower margin with 

 short hairs and tipped with long ones at the extremity; from the base of the mastigo- 

 branchia arises a well-developed podobranchial plume ; the lower and basal portion of the 

 posterior or inferior side consists of a series of trichobranchiate filaments, and on the 

 anterior portion, near the distal extremity of the same side, are several phyllobranchial 

 plates. On the coxa near the podobranchial articulation is a single bunch or fasciculus 

 i if Ions; hairs. 



The first pair of pereiopoda consists of six articulated joints, the basis and ischium 

 being fused together, leaving a distinct line of union defining the unused articulation 

 between the two joints. The right is much larger than the left, and the coxa supports a 

 short, curved, stiff, almost rudimentary, mastigobranchial process, thickly fringed with a 

 fur of short hairs along the lower margin, and tipped with long hairs that are serrate 

 along the sides ; from the base of the mastigobranchia arises a well-developed podobran- 

 chial plume, consisting of trichobranehial filaments attached to the stem from the base 

 to the extremity on the under side, and three phyllobranchiate plates at the distal ex- 

 tremity on the upper side, not far from the articulation of which, on the coxa, stand two 

 well-formed fasciculi of long hairs, fringed with minute, sharp, short cilia, similar to 

 those pointed out by Professor Huxley as existing in the genus Astacun. These two 

 fasciculi are distinct from each other, well defined, and the hairs are as long as the podo- 

 branchial plume. The left differs from the right in size but resembles it in form, and is 

 imperfectly chelate. The dactylos is long, arched, diagonally compressed, and reaches 

 considerably beyond the extremity of the short, sharp pollex of the propodos : it is 

 fringed with hairs upon the outer margin and with short blunt truncated denticulations on 

 the inner, and only at the base impinges against the anterior serrated margin of the 

 pollex: the propodos is quadrate, nearly as broad as long, compressed and slightly 

 rounded both on the inner and outer surfaces, flattened on the upper, and fringed with 

 strong hairs on the upper and lower margin; the carpos is short and triangular in 



