382 MRS. E. AV. SEXTON ON A [Apr. 28, 



no doubt, the reason why it escaped detection by Costa (2) (" priva 

 affatto di iinghia "). 



Setce. — The 2nd, 3rd, and 4th joints each carry a seta at the 

 posterior distal angle ; the 5th is covered on the anterior and 

 posterior surfaces with dense masses of delicate, hyaline, sensory 

 hairs (fig. 4), with a fringe of long jointed setse at the anterior 

 angle, and four clusters of the same along the posterior margin 

 (for detail see fig. 5). The 6th joint is thickly covei-ed with the 

 hvaline hairs, with a large number of the jointed set?e anteriorly, 

 increasing in length to the anterior angle, the longest being 

 twice the length of the joint ; the posterior angle also bears a 

 cluster of shorter, jointed setse. These " hyaline hairs " and 

 " jointed setce " are peculiar to the 5th and 6th joints ; the 6th 

 joint having yet another kind, stiflJ", curved, and serrate, similar 

 to that figured for T. raschii (PI. XX. fig. 3). A cluster of about 

 four to six of these is to be found on each side of the claw, and 

 three just beyond its tip. The claw itself is denticulated on its 

 under surface, and the portion of the margin against which it 

 impinges is thickly dentate (fig. 2). 



Per^eopoda. — Branchial vesicles occur on all the perteopoda, long 

 and much pleated on the first and second, shorter and more 

 divided on the three posterior pairs. Incubatory lamellae are 

 attached to the first three, as well as to the second gnathopod. 

 The sixth joint of each perseopod is produced over the base of the 

 claw in two delicate transparent plates, or " dactyloptera '"' (see 

 Spence Bate, 4. p. 317), with pectinate margins (PI. XYI. fig. 6). 

 The tactile spines of the perseopoda and viropoda are of similar con- 

 struction. Each consists of a stout shaft, blunt-tipped, carrying 

 subapically a slender flagellum (c/. PI. XVII. fig. 3). 



First Per^opod. — Female (PL XVI. fig. 7). 2nd joint long, 

 a little longer than the two following taken together, expanded, 

 rather narrowed proximally ; 3rd very small ; 4th long, a little 

 dilated anteriorly, 5th subequal to the 4th in length ; 6th longer 

 than the 5th, narrow ; the 7th or claw moderately curved, about 

 half the length of the 6th. 



^Qtce. — The 2nd and 3rd joints each carry one seta at the 

 posterior angle. The 4th has, anteriorly, one small seta and one 

 laro'e spine at the distal angle, with three setfe along the poste- 

 rior margin and one at the angle. The 5th has two setae at the 

 anterior angle ; one at the posterior, and four along the margin. 

 The 6th has one small seta at the anterior angle ; the posterior 

 margin is dentate, with seven strong setse inserted at intervals 

 along it. The claw is provided with eight denticles on the 

 proximal half of the inner margin. 



Male. 2nd and 3rd joints as in the female ; 4th and 5th slightly 

 longer, the 6th and 7th distinctly longer, than in the female. 



Sstce. — The posterior margins of the 4th and 5th have each one 

 seta more, and the 6th two setae more, than the female ; the 

 posterior margins of both the 5th and the 6th are dentate ; the 

 claw with ten denticles. 



