ISOPODA. 27 



ventral margin is nearly completely occupied by the same highly specialised setae. 

 Here they graduate in size to the distal extremity, where they rather quickly become 

 much larger than elsewhere. These setae (fig. 3) consist of a shaft with very finely 

 granular contents, the shaft tapers and ends in a blunt point, which in certain aspects 

 appears to be an elongated knob. Both margins are fringed with very delicate flat teeth, 

 very close, in fact contiguous to one another. These appear to be set on the shaft 

 at an angle so as to form the limbs of a V, of which the shaft forms a very broad 

 base. The ventral margin of the second joint is very minutely dentate. None of the 

 authors previously cited deal with this appendage in any detail. Eights describes 

 the left mandible as having " two corneous teeth, placed one within the other, that 

 on the right contains but one ; they are convex externally and internally concave, 

 with a small foramen at their base." This latter statement I do not understand. As 

 regards the palp, he states the two basal joints are subequal in length and the 

 terminal one about half the size. Dr. Studer states that the cutting edge is divided 

 into two ridges and bears no teeth, but only sharp undulating edges. This figure 

 is not good ; he omits almost all the setae on the terminal joint of the palp, but in 

 the comparative sizes of the joints they more closely resemble the ' Discovery ' 

 specimens. The only reference I have seen to the highly specialised setae is contained 

 in Dr. PfefFer's description of S. septemcarinata ( 11), and he figures them for that species 

 as being plumose to within a short distance of the enlarged end. 



The first maxilla (fig. 4) consists of two lobes. The inner one is very small and 

 delicate, the outer one large and strong. The inner one is irregularly ovoid upon a 

 short peduncle, the outer one is stout and slightly curved. Its cutting edge is hollowed 

 out to some extent, and the margin is fringed with stout spines of variable length, but 

 the largest are most anterior. In the specimen examined there are eleven of these. 

 The dorsal margin of this joint is covered with very minute teeth, which are replaced 

 by simple setae about the middle of its length. 



The second maxilla (fig. 5) is more delicate in structure, and comprises a thin but 

 broad inner lobe, rounded distally and there provided with upwards of thirty specialised 

 setae. About two-thirds the length of this lobe there arise externally two lobes of 

 approximately equal size. It would, perhaps, be correct to say a single bifid lobe. 

 Each of these lobes is armed distally with two stout specialised setae, similar to, but 

 much stronger than, those of the inner lobe. The setae are all pedunculate. A central 

 core runs continuously through the peduncle and shaft, and the latter is covered with 

 a number of very minute but stout spines. 



The maxilliped (fig. G) consists of a short but very broad sub-triangular plate, which 

 carries the large masticatory lobe, and an approximately rectangular epignath. The 

 inner margin of the masticatory lobe is straight, rounded towards the base, where 

 there is a group of rather long simple setae, and a few other small ones are scattered 

 along it. The anterior margin is nearly straight, and bears a stout tooth near each 

 angle. The outer tooth is situated in rather a deep depression. The outer margin 



L 2 



