EEPORT ON THE AMPIIIPODA. 1233 



With regard to the three S5 7 stems of arrangement proposed by Mayer in his 

 " Caprelliden," pp. 18, 19 (1882), Dodecas in the first will stand after Proto and 

 Protella, in the other two between Proto and Caprellina. 



Dodecas elongata, Stebbing, 1883 (Pis. CXXXIX., CXL.). 



1883. Dodecas elongata, Stebbing, Ann. and Mag. Nat. Hist., ser. 5, vol. xi. p. 207. 



Body smooth, sometimes more or less speckled, very long and slender ; the first and 

 second segments of the peraeon very long and slender in the male, much shorter and 

 rather thicker in the female, in both sexes the first broadest at its junction with the 

 almost completely coalesced head, and narrowest at its junction with the second segment, 

 which is broadest at the part where the limbs are attached ; the third and fourth 

 segments are shorter in the male, and much shorter in the female, than the fifth and 

 sixth ; in the female the third is widened distally, the fourth proximally ; in both sexes 

 the seventh segment is very short. 



Eyes prominent, round or a little oval, situate near the top and front of the head, 

 small, but with the ocelli very numerous. 



Upper Antennae large and long, the first joint of the peduncle stout, about as long as 

 the head, the second joint more slender, from two and a half to three times as long, the 

 third more slender and a little shorter than the second ; the flagellum showing in different 

 specimens seven, eight, or nine joints, of which the first is much the longest, with setules 

 at three or four points of the lower margin, the remainder having each an apical setule, 

 all except the last being a little dilated distally, the whole flagellum much shorter than 

 the fifth joint of the peduncle. 



Lower Antennae very slight in comparison with the upper, the flagella of which they 

 do not greatly exceed in length, nor in thickness at all, except at the base, the first and 

 second joints appearing to be completely coalesced, the gland-cone minute, the third joint 

 a Uttle longer and more slender than the preceding two, the fourth joint nearly twice as 

 long as the three preceding together, the fifth nearly as long as the third and fourth 

 together ; the flagellum of three, four, or five very slender joints, together not so long as 

 the last joint of the peduncle. 



Upper Lip distally rather deeply divided into two unequal lobes, the margin 

 smooth. 



Mandibles. — Cutting plate divided into five strong unequal teeth, of which the 

 lowest is bifid, the others sometimes assuming the same appearance from wear ; in one 

 specimen the right mandible had but four teeth, not showing any signs of loss or 

 breakage, while the new growth displayed the usual five ; the secondary plate, on the 

 left mandible nearly as large as the primary, its broad distal edge divided into five or 

 six teeth ; on the right mandible this plate is less powerful, its distal edge broad and 



(ZOOL. CHALL. EXP. PART LXVII. — 1888.) XxX 155 



