392 MRS. E. W. SEXTON ON A [Apr. 28, 



with a distinct nail and bears on its distal margin one small 

 bristle, similar to those of the lateral clusters. 



The large branchial vesicle reaches to the distal margin of the 

 3rd joint. 



The inciihatory lamella is lanceolate in shape, and extends to 

 the distal margin of the 2nd joint. It is bordered with fine, 

 delicate setfe of great length, the tips of which are slightly 

 expanded (fig. 2). 



In the young (PI. XX. figs. 6 & 7) the 3rd joint is only 

 half the length of the 2nd ; the 4th is small, half as long as the 

 5th, which equals the 3rd. The 6th is much larger than in the 

 adult, rounded, with the two masses of hyaline hairs, and four of 

 the long, jointed sette on the anterior angle. The claw also is 

 much larger, with a. distinct nail, three strong sette at the tip, and 

 one on the distal margin. 



SeUe. — The 2nd, 3rd, and 4th joints each carry one small seta 

 near the posterior angle ; the 5th has two of the long jointed 

 setse posteriorly, one small seta anteriorly, no hyaline hairs 

 developed. 



Per^opoda. — The 1st pereeopod is the longest, the 3rd the 

 shortest ; the three posterior pairs successively increase in length. 

 Branchial vesicles are attached to all ; incubatory lamellse to the 



First Per.^opgd.— .4cZ?tZ« (PI. XX. fig. 8). The 2nd joint is 

 very long, broad ; 3rd short ; the 4th long, with a laminar ex- 

 pansion anteiiorly ; the 5th ovate, shoi'ter than tlie 4th ; the 

 6th narrow, subequal to the 4th ; the 7th half the length of the 

 6th, with a distinct falciform nail, the posterior margin with a 

 slight excavation proximally. 



Setoi. — The 4th joint carries five spines anteriorly; these spines 

 are similar in construction to those of T. uicceense, but with the 

 flagellum much shorter and nearer the apex. There is one spine 

 at the posterior angle, and, indented in the posterior margin, are 

 two small sensory setules. The 5th joint carries three of these 

 setae anterioily, two posterioidy, and six spines around the poste- 

 rior angle, one considerably larger than the others. The 6th and 

 7th have their posterior maigins thickly dentate, the anterior 

 margins serrate, the sixth joint with three spinules inset in the 

 posterior fringe, two in the anteiior, and three at the anterior 

 angle. 



The branchial vesicle at its widest is only half the width of the 

 one attached to the second gnathopod. 



The immature has the 4th joint expanded. 



In the young (PI. XX. fig. 9) the proportions of the joints 

 are very difierent, the 4th, 5th, 6th, and 7th being practically 

 subequal. The 4th joint is not expanded. 



Setce. — The 2nd, 3rd, 4th, and 5th are each provided with a 

 small seta at the posterior angle, the 6th with one at the anterior 

 angle. 



Second Per^opod. — Adult (PI. XX. tigs. 10 &, 11). 2nd joint 



