HKPORT ON THE CRUSTACEA MACRURA. 15 



consists of seven joints, and is formed on the same general type. The basisal joint 

 is short and irregular, and carries a long branch consisting of three joints, which is 

 generally at right angles with the gnathopod, and lies parallel with that of the 

 first pair, and stands upright by the side of the mouth. The first joint of this branch 

 is long and cylindrical ; the second is more slender, and lies generally at right 

 angles with the first ; and the third consists of a multiarticulate flagellum fringed with 

 long slender hairs. The third joint (ischium) is lung and angular (the internal margin 

 has on the interior angle a strong projecting process, and has one strong spine a little 

 beyond the centre) ; the fourth joint is about half the length of the third, is angular, and is 

 armed with three teeth or spines on the inner margin ; the fifth joint is scarcely longer than 

 the fourth, and increases in diameter towards the distal extremity, where the outer angle 

 supports a small brush of long hairs: the propodos, or sixth joint, increases in diameter 

 towards the extremity, where the inner angle is produced into a polliciform lobe, and is 

 tipped with a brush of long and strong hairs : the outer distal angle also has a small brush 

 of cilia ; the dactylos, or seventh joint, scarcely reaches beyond the extremity of the 

 corresponding process of the propodos, against which it impinges and forms a cheliform 

 extremity — a character, in my experience, that is unique among the higher Crustacea. 

 Such a chela exists in some of the Edriophthalmous Crustacea, but, as far as I am aware, 

 the form has not been previously observed in the Podophthalmia. 



The next pair of appendages is the first of the pereiopoda. It is a large and 

 powerful pair of organs, the peculiarity of which lies in the formation of the carpos and 

 propodos : the limb, as far as the carpos, is laterally compressed and directed forwards, 

 when it is suddenly compressed transversely, and abruptly bent downwards at an acute 

 angle : the anterior or upper surface of the reflexed portion of the carpos, as well as that 

 of the propodos and dactylos, is compressed flat. The outer margin is curved and the 

 inner strait, so that when the. right and left limb are brought together they, being of 

 equal size, form a nearly oval plane, the upper or carpal portion of which is fringed with 

 a row of equidistant comb-like dentations. The dactylos is sharply pointed, and impinges 

 closely against the pollex, which it overlaps at the extremity. 



The second pair of pereiopoda is of the normal form, and consists of seven joints, of 

 which the carpos, propodos, and dactylos are subequal in length. 



The third pair resembles the second both in size and form, and in the female carries 

 the vulva? in the form of a large circular opening on the posterior surface of the coxa. 

 The coxa of these two pairs of legs approach each other more closely than those of the 

 two following pairs, which are smaller and wider apart. 



The fourth pair terminates in a small sharp dactylos which is considerably and suddenly 

 smaller than the propodos. The fifth or last pair of pereiopoda has the distal extremity 

 of the propodos enlarged and covered with a thick pavement of small tubercular spiculi- 

 form points. 



