DEVELOPMENTAL PHASES 355 



The telson is considerably elongated and the uropods well developed. There is one pair of ventro- 

 lateral spines, three pairs of postero-lateral, and seven terminal spines. 



Second furcilia. Nineteen specimens examined (Fig. 8h-k). Length range 3-7-4-1 mm.; average 

 length 3-9 mm. 



In this stage there are four pairs of setose pleopods and one pair of non-setose. 



The types encountered with mixed setose and non-setose pleopods were as follows : (a) those with 

 four pleopods: one setose, three non-setose; (b) those with four pleopods: two setose, two non- 

 setose; (c) those with four pleopods: three setose, one non-setose; (d) those with five pleopods: two 

 setose, three non-setose ; (e) those with five pleopods : three setose, two non-setose ; (/) those with five 

 pleopods : four setose, one non-setose. 



Table 7. Development of three species of Nyctiphanes 



N. = non-setose, s. = setose; stages 5 and 6 have the antennal endopod segmented. 



The data for N. couchii are taken from Gurney (1942) and those for N. simplex from Boden (1951). 



Altogether, 286 larvae of this stage were identified in the following numbers: (a) 20, (b) 19, (c) 10, 

 (d) 14, (e) 28, (/) 195. Of these, type (c) has previously been reported in the literature only for 

 Nyctiphanes anstralis. 



The frontal plate is about as long as it is broad and is somewhat more elongate but still unsegmented. 



The second antenna is the same. 



The first cormopod is as in the previous stage. The second is bifurcate, segmented, and carries 

 a bilobed gill. The third cormopod is bifurcate, unsegmented, and carries gill rudiments. The re- 

 maining cormopods are still bud-like. 



The telson has seven terminal spines. The uropods are longer and better developed than in the 

 previous stage. 



Third fine ilia. Ten specimens examined (Fig. ga-e). Length range 4-0-4-4 mm.; average length 

 4-2 mm. 



In this stage there are five setose pleopods, the antennal pleopod is unsegmented and there are 

 (a) seven, or (b) five terminal spines on the telson. Forty-one specimens of type (a) were encountered 

 and one hundred and fifty of type (b). Four specimens with six terminal spines were found, each of 

 them abnormal in this respect (Fraser, 1936; John, 1936). 



The frontal plate is longer than it is broad and its anterior margin is concave. 



3-2 



