860 MRS. E. W. SEXTOX ON AMPHIPODA [Nov. 23, 



itself, the outer lobes thus completely hiding the small inner 

 ones ; it requires to be straightened out before its true construction 

 can be seen, and this, because of its extreme tenuity, is a diffi- 

 cult matter. This appears to be the explanation of Chevreux's 

 statement ; the specimen he examined was a young animal with 

 the lower lip conti-acted. 



Mandibles strong (figs. 24, 25, 26, & 27). Cutting-plate of the 

 right mandible in the large female with the margin divided into 

 7 teeth, the two below very large ; accessory plate (fig. 26) large, 

 almost as large as that of the left mandible, but of more delicate 

 structure, produced below to a curved tooth, upper portion of the 

 margin crenulated, with 2 small teeth. In the young female the 

 cutting-plate has 6 teeth (the two uppermost ones being very 

 small) and the margin of the accessory plate is much more 

 dentate than in the older animal, probably less worn (fig. 25). The 

 accessory plate being pellucid and lying flat against the cutting- 

 plate, is no doubt the i"eason it escaped Chevreux's notice. In 

 the male the cutting-plate is divided into 6 teeth ; the accessory 

 plate is of the same construction as that of the female but with 

 the inferior margin straight, not curved (fig. 27). 



Left mandible (fig. 24). — In both male and female the cutting- 

 plate is divided into 6 teeth, the second lowest being the largest ; 

 the accessory -pilate margin into 5 teeth. The figiu^e given by 

 Chevreux is scarcely accurate. The right spine-roio, male and 

 female, contains 7 spines, the left 8, each with a plumose brush- 

 like seta behind ; the spines have a downy appearance, being 

 covered with microscopic spinules. Molar prominent, cylindrical ; 

 the crown is ridged transversely with small rows of teeth ; it is 

 surrounded with fine hairs, and carries a long ciliated hair pos- 

 teriorly. In the female the crown of the left molar is ridged all 

 over, but the anterior portion of the crown of the right molar 

 is smooth. Palp very large ; 3rd joint unusually long, much 

 longer than the 1st and 2nd taken together; the distal half of 

 its anterior margin is bordered with strong bristles (19 in the 

 female, 17 in the male), the 5 apical ones set at a different angle 

 from the others, and feathered on both sides, while the remaining 

 ones are feathered on one side with cleft tips ; the middle bristle 

 in the apical group is twice the length of the others. In 

 addition to these a diagonal row crosses the joint proximally on 

 the outer side ; and the tip of the joint is covered with minute 

 spines. The 2nd joint is produced a little anteriorly, like, but in 

 a less degree, to that of S. latijjes ; it carries a group of bristles 

 distally. 



First maxilla (fig. 29). — Inner plate small, with 2 long, and 2 

 minute plumose hairs ; outer plate in the female with 7 spines, 

 4 large, strong, furcate, and the other 3 longer, each with about 

 6 small teeth. The male has the same number of spines, but 

 fewer teeth on the spines. Palp biarticulate, longer than the 

 outer plate ; apex with a row of 5 feathered spines on the margin 

 and 3 feathered setce submarginally. 



