1908.] GENUS OF AMPHIPOB CRUSTACEA. 381 



"tudinal ridges of chitin on all the free joints. The 2nd joint is 

 very long and curved ; the 3rd, 4th, and 5th are subequal, the 

 3rd and 4th continuing the curve of the 2nd ; the 5th with a 

 longitudinal ridge produced to a point on each side of the articu- 

 lation with the 6th (see fig. 6). The 6th or " hand " is usually 

 ■carried as in fig. 6, immensely swollen, with the inner side (fig. 8) 

 rounded and more swollen than the outer (fig. 7). The palm 

 margin is bordered with strong, incurved, mobile teetii, 15 in 

 number, each with a tubercle behind (see fig. 8, detail), and with 

 five long, slender, mobile spines above the margin. The hand 

 has the deep groove or channelling described by Costa, " una 

 scanalatura nella faccia esterna," into which the acuminate tip of 

 the long claw fits. At the prehensile angle, on the outer edge of 

 this groove is a very long, mobile, curved sjoine, with a small one 

 beside it, each with a tubercle posteriorly, while on the under 

 edge are two medium-size spines, one lai-ger than the other ; all 

 four spines are j)rovided with small flagella. The jjowerful curved 

 •claw or " finger " is very long, longer than the palm margin, with 

 12 or 13 minute sensory setules along its inner surface. 



The only diflference between the sexes is — in the male the hand, 

 Avhile equally broad, is slightly longer than that of the female, and 

 the palm margin is provided with more spines. 



Females. In the ' Huxley' specimen, 23 mm,, the width of the 

 hand is 2*5 mm., with 5 long spines and 15 small teeth on the 

 palm margin ; hand figured (fig. 7). Of the Irish specimens, 

 the first 20*5 mm, long measures 3 mm, across the hand, with 5 

 long and 16 small teeth, hand as fig. 6 ; in the second specimen, 

 20 mm., the hand measures 3 mm., 5 long and 18 small teeth, 

 hand inverted ; in the third female, 22 mm., the hand measures 

 2*75 mm., 5 long and 18 small teeth, hand as fig. 7, 



Males. In the specimen figured, 21'5 mm. in length, the hand 

 measures 3 mm., 6 long and 19 small teeth (fig. 6), The second 

 specimen, 21*5 mm,, is exactly similar; the third of 20 mm, 

 length measures barely 3 mm. across the hand, 6 long and 18 

 small teeth, hand carried as in fig, 6, 



Second Gnathopod (PI. XVI. figs. 1, 2, 3, 4, & 5).— The 2nd 

 joint is very long and slender, curved, widening distally; the 

 3rd is rather more than two thirds the length of the 1st, longer 

 than the two following taken together, laminar, the distal half of 

 the joint wider than the proximal ; the 4th joint is small, narrow 

 proximally, twice as wide at the distal end, rounded posteriorly, 

 with the posterior margin twice the length of the anterior ; the 

 5th is longer than the 4th, ovate elongate, narrow at both 

 extremities, considerably expanded posteriorly ; the 6th bends 

 backward towards the 5th, almost discoidal in shape, as wide as 

 long, very narrow proximally, but expanding both anteriorly and 

 posteriorly. The 7th joint or claw is very minute, set trans- 

 versely in the middle of the distal margin of the 6th, so that the 

 point of the claw impinges against the under surface of the margin. 

 It is completely concealed by the dense masses of setse, which is 



