REPORT ON THE CRUSTACEA MACRURA. 31 



The first pair of antennas has the two flagella nearly equal in length, but the 

 primary is the larger, and is furnished with numerous membranous cilia near the 

 extremity. The secondary flagellum is slender and almost destitute of cilia; both 

 flagella have the artieuli strongly defined. 



The second pair of antennas has only the peduncle preserved, and this is nearly as 

 long as the first. 



The second pair of gnathopoda is pediform. The coxa and basis are short. The 

 ischium is long, and has the infero-internal margin strongly serrated. The meros, . 

 earpos, and propodos are subequal ; the dactylos is wanting. Each of the joints is 

 copiously supplied with long hairs, more particularly on the under margin. 



The posterior pair of pereiopoda is small, and terminates in a chelate hand immersed 

 in a brush of hairs. 



The first pair of pleopoda is slender, feeble, and single-branched. 



The second pair is long, slender, and double-branched, the inner ramus being two- 

 jointed ; a few long hairs fringe the termination of each joint. 



The next three pairs of pleopoda consist of large foliaceous plates. The margins of 

 the inner plate are thickly fringed with strong multiarticulate hairs, furnished with short 

 cflia on both sides ; the inner margin carries a short, stout stylamblys, the apex of which 

 is crowned with small obtuse-pointed hooks (cincinnuli). The outer plate has the outer 

 margin fringed with long multiarticulate hairs, ciliated on one side only, while the inner 

 margin carries a row of distantly placed, solitary, simple straight hairs. 



The posterior pair of pleopoda (the rami of the rhipidura) has the outer branch much 

 larger than the inner. The peduncle is short, and the foliaceous plates somewhat pear- 

 shaped in form. The posterior margin of the outer plate is thickly fringed with both 

 long and short spines, and hairs, plain and ciliated, some of which on the inner angle 

 increase in size and length until they become long and stout spines, with a slight curve 

 or hook at the extremity. These are repeated for a short distance on the outer corre- 

 sponding angle of the inner plate, where the spines are curved in the opposite direction, 

 and mingled with hairs only that are fringed with long cilia. On the posterior lateral 

 margin of the telson there are, mixed with the ciliated hairs, two sharp, short spines on 

 each side. 



Observations. — Our specimen has the branchiae approximating closely to those of 

 Callianassa both in arrangement and in character. They consist of four pairs of arthro- 

 bi-anchias and one podobranchia according to the following formula : — 



Pleurobrancbiae, . . . . 



Arthrobranchiae, . . . . 2 2 2 2 ... 



Podobranchiae, . . . ... 1 



Mastigobranchice, . . 



h i k 1 m n o 



