2s6 



DISCOVERY REPORTS 



Table I. Showing the Fur cilia forms which were found, and 

 the numbers of each, in five species of Euphausia 



Furcilia forms 



Forms recognized by the character and number 

 of the pleopods. Antennal endopod unseg- 

 mented: 

 I pair of non-setose pleopods 



3 pairs of non-setose pleopods 



4 pairs of non-setose pleopods 



5 pairs of non-setose pleopods 



I pair of setose, 2 pairs of non-setose pleopods 



1 pair of setose, 3 pairs of non-setose pleopods 



3 pairs of setose, 2 pairs of non-setose pleopods 



4 pairs of setose, i pair of non-setose pleopods 



5 pairs of setose pleopods 



fWith 7 terminal spines on telson 

 fWith 6 terminal spines on telson 

 {with 5 terminal spines on telson 

 Forms recognized by the number of terminal 

 spines on the telson. Antennal endopod 

 segmented : 

 8 terminal spines on the telsonj 

 7 terminal spines on the telson 



6 terminal spines on the telson 

 5 terminal spines on the telson 

 4 terminal spines on the telson 

 3 terminal spines on the telson 



2 terminal spines on the telson 

 I terminal spine on the telson 



E. 



frigida* 



E. 

 vallentini 



I 

 123 



I 



194 

 220 



219 



I 



4 



(2) 

 117 



(4) 

 44 



(10) 



98 



62 



3 



47 



135 



47 



7 



57 



£. 



triacantha 



310 



5 



I 

 343 

 247 



All 



20 



(12) 

 93 



(15) 

 111 



(2) 

 136 



(II) 

 71 



(I) 

 11 



(3) 

 16 



E. 



longirostris 



18 



6 

 14 



All 



E. 



spinifera 



11 



I 

 2 



5 

 8 



All 



(I) 

 6 



(3) 

 6 



4 

 6 

 9 



In the second group the number of those individuals with even numbers of terminal spines are enclosed in 

 brackets to indicate that they are regarded as abnormalities and not as variants of equal value to those in the 

 first group having unusual numbers of pleopods. 



* Compare with Rustad's results quoted above; his three dominant forms are the same as the first three 

 of my Furcilia stages. 



f The numbers of E. vallentini are of iii specimens in which the telsons were complete. 



I Eight terminal spines have not previously been recorded, so far as I am aware, for any larval euphausiid. 



It is important to notice that although the succession of stages is not the same in the 

 two groups of species, a higher stage of either series arises from the one below it by the 

 non-setose pleopods of the latter becoming setose, and, if the number of pleopods is 

 not already five, by the addition of a pair or of pairs of non-setose pleopods. This is 

 shown diagrammatically in Fig. 34. The five squares of each rectangle represent the 

 first to fifth abdominal segments of an individual, the first on the left, the fifth on the 

 right; a simple line represents a non-setose pleopod, a line forked at the end a setose 

 pleopod. 



These I regard as the earlier Furcilia stages of the two groups of species because they 

 are, certainly in the first group and almost certainly I think in the second, the instars by 

 which development proceeds in the vast majority of the individuals. They are described 

 in the pages that follow as Furcilia I-III of the first group, Furcilia I-IV of the second. 



