DEVELOPMENT OF EUPHAUSIA SUPERB A 



91 



First thoracic limb. The form of the ist thoracic appendage (Fig. 22 a) is not much 

 altered, the endopod is five-segmented and heavily setose, and the exopod, as before, 

 primitive in shape and bearing four bristles distally. The joint at the base of the endopod 

 is not clear. The length of the limb is about three-quarters that of the succeeding thoracic 

 appendage. 



e III 



a, thoracic limb I ( x 35); 



b, thoracic limb II ( x 35); 



</lV dy 



Fig. 22. Fourth Furcilia (continued). 



d, gills I-VII, the base of Th. VI and vestigial Th. VII in 

 front of luminous organ ( x 83); 

 c, thoracic limb VI, lateral aspect ( x 35); e\, e ii, e iii, pleopods I, II and III ( x 35). 



Thoracic limbs II-VIII. Thoracic hmbs II-VIII are not greatly changed (Fig. 22 b, 

 c). The exopods bear the following numbers of setae: 



Th. II inner margin 11, outer margin 7 



in „ 13 „ 8 



IV „ 13 „ 8 



V „ 13 „ 8 



VI „ II „ 7 



Situated on the inner side of the yth gill and anterior to the luminous organ is a 

 small digitate process not apparently branchial in function which is the vestige of the 



