DEVELOPMENT OF E. VALLENTIXI 273 



The antennular peduncle is of three segmentSj the spine from the first segment as long 

 as the sum of the second and third. 



The second, the second and third, or the second, third and fourth thoracic limbs are 

 represented by sac-like buds, the second bigger than the third, and so on, enclosed in 

 a common integument. The second may show the beginnings of bifurcation ; the fourth 

 appears to be more commonly represented by a bud than it does in the same stage of 

 E. frig id a. 



The abdomen is of seven segments and one and a half times as long as the carapace. 

 There are seven terminal spines on the telson which become progressively smaller from 

 the outside to the centre. 



Furcilia, stage I (Fig. 37 ^) 



Description based on the examination of thirty specimens. Forty-five were measured and were 

 3 •2-4-0 mm. long. 



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



The carapace of all but a very few of those examined had a well-defined dorsal organ, 

 an unmistakable abrupt protuberance. The frontal plate is rectangular with the distal 

 corners nearly square in the smaller, more rounded in the larger. It is usually nearly as 

 long as broad, rarely a little longer than broad (Fig. 37 d) — never so wide nor so square 

 as in E. frigida. 



The spine from the outer distal corner of the first antennular segment is usually 

 nearly equal in length to the sum of the second and third segments, sometimes equal 

 to it. 



The most usual condition of the thoracic limbs is that the buds of the second and 

 third are free (they are so in all thirty), and those of the fourth to eighth enclosed in 

 a common integument ; the second bifurcate, from a quarter to more than half the length 

 of the first ; the third not bifurcate. The third may be bifurcate and the bud of the fourth 

 may be free ; very rarely the second limb buds show the beginnings of gills. 



Small lateral projections of the tergum of the first abdominal somite are present. The 

 abdomen is nearly twice as long as the carapace. The uropods reach nearly to, or to the 

 lateral spines of the telson. 



Furcilia, stage II (Fig. 37 e, f) 



Description based on the examination of twenty specimens. Forty-two were measured and were 

 4-5-5 -I mm. long. 



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



The carapace has a conspicuous dorsal organ. The frontal plate narrows distally and 

 is rounded so that it has the shape of a " rounded triangle". There is usually a diminutive 

 spine in the centre of the anterior margin (Fig. 37/). In some the spine is wanting and 

 the shape is less nearly triangular. 



The antennular spine reaches two-thirds of the way, or less frequently halfway, along 

 the third peduncular segment; the flagella are short and unsegmented. 



