DEVELOPMENT OF E. FRIGIDA 265 



Stage III. With 5 pairs of setose pleopods, antennal endopod unsegmented, 7 terminal 



spines on telson ... ... ... ... ... ... ... ... ... 220 



With 5 pairs of setose pleopods, antennal endopod unsegmented, 5 terminal 



spines on telson ... ... ... ... ... ... ... ... ... i 



With antennal endopod segmented, 7 terminal spines on telson ... ... 4 



With antennal endopod segmented, 6 terminal spines on telson ... ... 2 



Stage IV. With antennal endopod segmented, 5 terminal spines on telson ... ... 117 



With antennal endopod segmented, 4 terminal spines on telson ... ... 4 



Stage V. With antennal endopod segmented, 3 terminal spines on telson ... ... 44 



With antennal endopod segmented, 2 terminal spines on telson ... ... 10 



Stage VI. With antennal endopod segmented, i terminal spine on telson ... ... 98 



All of these are from the Falkland Sector of the Antarctic. 



Although Rustad (1930) has described the second and third Calyptopis stages, as well 

 as the first of which I have none, I have thought it well to give my own descriptions of 

 them in the terms and detail I use for describing later stages of this species and these 

 and later stages of other species. 



The larval stages of E. frigida are very similar to those of E. vallentini. 



Second Calyptopis (Fig. 36 a) 

 Description based on the examination of eight specimens, 1-7-1 -8 mm. long.^ 

 The carapace is rounded anteriorly and is hood-like, coming down far in front and 

 on either side of the head. It broadens out laterally from a point anterior to the middle 

 point of the lateral margin. The upper hinder angle appears in side view to be faintly 

 pointed because of the small and gently rounded projection in the middle of the pos- 

 terior margin. There is no definite dorsal organ, but there may or may not be a small 

 less characteristic projection in the region. 



The antennular peduncle is of two or of three segments ; the flagella are represented 

 by small single segments. The other appendages, the antennae to the first thoracic limbs, 

 are similar to those of other described Calyptopis. The limbless second to eighth 

 thoracic segments are easily seen as narrow encircling folds of the integument. 



The abdomen is of six segments and equal in length to the carapace. The posterior 

 margin of the telson is rounded and there are seven terminal spines. 



Third Calyptopis (Fig. 36 b) 



Description based on the examination of seventeen specimens. Twenty-three were measured 

 and were 2-5-2-9 mm. long. 



The carapace seen from above or below, or better still at an oblique angle from above 

 or below, is constricted immediately behind the eyes and then broadens out laterally 

 and ventrally into faint postero-lateral wings. There is as in the preceding stage a low 

 and gently rounded projection in the middle of the posterior margin. A denticle is 

 present on each of the lateral margins near the posterior end. There may or may not be 

 a small but definite projection in the region where the dorsal organ occurs in other species. 



^ Rustad (1930) gives the length as about 1-5 mm. 



