3o6 DISCOVERY REPORTS 



sometimes feeble or obsolete. The dorso-lateral tubercles on the hind margins of seg- 

 ments 2 and 3, present in the Terra Nova $, are here only very feebly developed or 

 quite obsolete. Segment 5 is smooth. A short fine pubescence dorsally on segments 3 



and 4 in?. 



Antenna 1, flagellum 17-18-jointed in <J, 15-16-jointed in $. Antenna 2, flagellum 



8-jointed in S, 5-jointed in ?. 



Gnathopod 2 similar to that of Dodecasella elegans. 



The rudiment of peraeopod 1 tipped with two setules. Peraeopods 4 and 5 of the 

 type found in Dodecas reducta, i.e. with the 6th joint 

 stouter than in D. elongata, but cylindrical, with two 

 pairs of spines proximally and one to two single 

 spines in middle of inner margin. 



Branchiae on segments 3 and 4 elongate ovate, II ~V_ c 



two-fifths to one-third length of their segments. \^ b 



Brood lamellae with posterior margin of the anterior 

 pair setose. \s /f 



Colour (as preserved) yellowish white, with X^ 



scattered reddish or purplish stellate specks, eyes a d 



reddish-brown. Fig. 169. Peraeopod 1 of: a. Dodecas 



_ m, ,. r J 1* * * A 00 n^A elonsata, hexacentrum, and Dodecasella 



Remarks. The discovery of adult <J<J and $$ and ^^ L Dodecas reducta . c . Aeginoides 

 juveniles in the same haul (no. 7) confirms the gauss ^ aberrat i on . d. Aeginoides gaussi, 

 identification of the Terra Nova <J and ? , and enables normal. 

 one to complete the diagnosis of the species. 



The tubercles or spines on the adults are evidently subject to variation. It would seem 

 that the lamella on segment 4, which Schellenberg interpreted as the rudiment of 

 peraeopod 2, is really the developing lateral tubercle of the adult. 



Distribution. 65 59' S, 89 33' E, 350 m.; off Cape Adare and Oates Land, 82- 

 366 m. 



Aeginoides gaussi, Schell. (Fig. 169 c, aberration). 

 Occurrence: With other specimens from St. 195 as above. 



Remarks. A single immature $, 20 mm. in length, found among the above-mentioned 

 adult and young specimens of the typical form, is very interesting because it shows on 

 what slender grounds some of the genera of this family are based. 



In form, tubercles and other features it is indistinguishable from the typical speci- 

 mens, but peraeopod 1 is composed of 3-i- joints. The terminal joint is minute. One can 

 only regard this specimen as a casual aberration, a reversion to the ancestral form where 

 the limb was composed of the normal number of joints. It helps to bridge a gap, and 

 one can form a series from Proto, through Dodecas (elongata and hexacentrum), Dodecas 

 reducta and this specimen, to the typical Aeginoides and Caprellinoides, in which latter 

 all trace even of a rudiment of peraeopod 1 has disappeared. 



