DEVELOPMENT OF E. SPINIFERA 301 



The spine from the third abdominal somite is as long as or longer than the fourth 



somite. The telson is narrower than in the previous stage ; it still has, as in earlier stages, 



only one pair of lateral spines. The innermost of the three pairs of postero-lateral spines 



is very strong and long — now the longest of the three (Fig. 40 h). 



Furcilia, stage VI (Fig. 40 /, k) 

 Description based on the examination of five specimens, 7-5-8-2 mm. long. 



In this stage there are three terminal spines on the telson. 



The dorsal organ may be high or it may be a low crest. The frontal plate is square with 

 rounded corners and a denticulate margin, a little reduced compared with that of the 

 previous stage ; the rostral spine is stronger and longer but reaches only to the end of the 

 first segment of the antennular peduncle. In three of the specimens the posterior pro- 

 jection of the carapace reaches beyond the end of the first abdominal somite ; in one it is 

 shorter; in the fifth it is but a short stump reaching no farther posteriorly than the 

 postero-lateral wings of the carapace (Fig. 40 i)} 



The antennular spine may still reach as far as the end of the third segment of the 

 peduncle. The first segment may have a small simple lappet and the third the beginnings 

 of a carina. 



The mandibular palp is unsegmented and non-setose in four specimens, but it is 

 indistinctly segmented and setose in the fifth. 



The thoracic limbs of the specimen 7-5 mm. long are as follows: 



First limb. Endopod of five segments, as long as to knee of second, feebly kneed. 

 No gill bud. 



Second to fifth limbs. Endopods long and kneed. Gills of three branches. 



Sixth limb. Very short. Endopod of three segments. Gill of three branches. 



Seventh limb. A gill of four large branches. 



Eighth limb. A gill of two small branches. 



The tergal wings of the first abdominal somite may be simple in shape as in previous 

 stages or they may be becoming rectangular. The spine of the third somite is as long as 

 or longer than the fourth somite (Fig. 40 k). The telson is narrow with one or two pairs 

 of lateral spines. 



Furcilia, stage VII 



Description based on the examination of nine specimens. One was 7-8 mm. long and two each 

 were 8-5, 8-6, 8-7 and 9-0 mm. long. 



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



The dorsal organ is high in all the specimens (compare with the previous stage). 

 The frontal plate may be somewhat reduced, but it is still square with rounded corners 

 and strongly denticulate margins. The rostral spine is much stronger, rising with a wide 

 triangular base from the frontal plate and reaching in all but two specimens to halfway 

 up the second segment of the antennular peduncle ; in one specimen it is much shorter, 

 1 Compare with the next stage: the reduction of this projection appears to be rapid. 



