DEVELOPMENT OF E. LONGIROSTRIS 285 



The telson is a little narrower, the innermost pair of postero-lateral spines a little 

 longer and stronger, than in the previous stage. 



Furcilia, stage VII (Fig. 38 k) 

 Description based on the examination of thirteen specimens, 8-5-1 1-4 mm. long.^ 



In this stage there is one terminal spine on the telson. 



The frontal plate is a little smaller than in the previous stage; the rostrum reaches 

 from nearly to, to beyond, the end of the first segment of the antennular peduncle. The 

 dorsal organ and crest are as in the previous stage. 



The antennular spine may be as long as or longer than the second segment of the 

 peduncle. The beginnings of the lappet of the first segment may be present. 



The thoracic limbs of twelve specimens, from 9-0 to 11-4 mm. long, were as follows : 



First limb. Endopod nearly as long as that of second. 



Fifth limb. Endopod long and kneed. 



Sixth limb. Endopod as long as to knee of fifth or longer, feebly or strongly kneed. 



In the smallest specimen taken, only 8-5 mm. long, the fifth limb is considerably 

 shorter than the fourth, the sixth only half the length of the fifth and not kneed. 



The gills of five specimens were examined. In four they were as in the five specimens 

 of the previous stage ; in the fifth as in the sixth specimen of the previous stage. It 

 appears then that specimens of Furcilia stage VII may have gills no farther developed 

 than those of stage IV. 



Development of Euphausia longirostris 



Dohrn (1871, pi. xxx, fig. 54) figured the second Calyptopis of E. longirostris without 

 recognizing it as the larva of a euphausian ; it is described as from the Indian Ocean. 

 In the Challenger collection, Sars (1885, p. 170, pi. xxxi, figs. 30, 31) found and de- 

 scribed a single specimen of a Furcilia with one pair of non-setose pleopods ; he con- 

 sidered it to be a larva of a large species of Euphausia. Tattersall (1924, p. 22, pi. i, 

 figs. 1-7; pi. ii, figs. 1-4), reporting on the Terra Nova collection, first recognized 

 E. longirostris larvae for what they were. Describing his specimens in my terms he 

 found : 



I specimen of Furcilia, stage I 4 specimens of Furcilia, stage V 



I specimen of FurciHa, stage II i specimen of Furcilia, stage VI 



4 specimens of Furcilia, stage III 2 adolescents 



9 specimens of Furcilia, stage IV 



He found in addition one larva {op. cit., pi. i, fig. i) with one pair of non-setose pleo- 

 pods "so strikingly different from the later stages. . .that he hesitated for a long time 

 before including it in the series". It is quite clear, now that the second and third 



1 Since specimens of the previous stage were found of a length of 11-7 mm. it is probable that specimens 

 of this stage are sometimes much bigger than any taken by me. 



