288 DISCOVERY REPORTS 



thoracic segments without Umbs are clearly visible as narrow encircling folds of the 



integument. 



The abdomen is of six segments. The telson is short, wider distally than proximally ; 

 its margins between the lateral and postero-lateral spines are concave ; the distal margin 

 is emarginate with seven terminal spines, the innermost of which is much smaller than 

 the others. Each of the postero-lateral spines has a secondary spine arising from it ; 

 the middlemost of the three pairs is much the longest (Fig. 39 b). 



Third Calyptopis (Fig. 39 c) 



Description based on the examination of ten specimens. Twenty were measured and were 

 3'3~3'6 mm. long. 



The dorsal organ is high, abrupt and conical. The part of the carapace anterior to the 

 constriction behind the eyes is larger in proportion to that behind than in the second 

 Calyptopis. The entire margin of the carapace is closely set with strong denticles ; the 

 single pair of lateral denticles do not appear in this stage of this species as they do in 

 each of the others described in this paper. The median posterior projection of the cara- 

 pace is of much the same proportions as in the second Calyptopis. 



The antennular peduncle is of three segments ; the spine from the outer distal corner 

 of the first is longer, or much longer, than the sum of the second and third. The flagella 

 are represented by small single segments. 



None of the second to eighth pairs of thoracic limbs is present as a free bud. 



The abdomen is of seven segments. The hinder lower edges of the pleura are denti- 

 culate. The posterior lateral margins of the sixth somite are produced backwards to give 

 a pair of short spines, one on either side of the telson as in the Furcilia stages of E. 

 triacantho ; they persist to the last Furcilia stage. 



The telson is large, longer than the fourth to sixth somites, with its distal end 

 expanded. 



Furcilia, stage I (Fig. 39 d, e) 



Description based on the close examination of ten specimens; sixteen were measured and were 

 4-2-4-7 mm. long. 



In this stage there is one pair of non-setose pleopods. 



The dorsal organ is a high cone rising abruptly from the carapace (Fig. 39 d). The 

 frontal plate is very wide with an emarginate anterior margin and broadly rounded 

 corners (Fig. 39 e). Its free edge is closely set with denticles, smaller on the lateral 

 margins, stronger on the anterior. The margins of the carapace from the antero-lateral 

 spines to the lateral denticles, which appear in this stage as short wide-based projections, 

 are closely beset with denticles. There are no denticles along the margins of the con- 

 cavities between the antero-lateral spines and the base of the frontal plate, and none 

 posterior to the lateral denticles. The median posterior projection usually reaches as far 

 back as the end of the second abdominal segment, but in one of the specimens it was 

 very short and thick. 



