3o6 



DISCOVERY REPORTS 



to it, the third about twice as long as the second, but narrower, the fourth about a third 

 the length of the third. The flagellum is slightly shorter than the peduncle ; the first six 

 joints are sub-equal, shorter than the fourth peduncular joint; the seventh flagellar 

 joint is very short and about half the width of the sixth. The terminal joint is very narrow, 

 but about equal in length to the sixth, with four delicate setae at its distal extremity. 

 An olfactory seta is present at the distal end of each of the joints of the flagellum except 

 the first two and the terminal one. The antenna is nearly twice as long as the antennule 

 and consists of a peduncle of five and a flagellum of ten joints. The first peduncular joint 

 is very short. The second and third longer and sub-equal, the fourth almost twice, and 

 the fifth two and a half times as long as the third. The anterior borders of the third, 

 fourth and fifth joints bear a series of tufts of long hairs. The flagellum is about equal in 

 length to the fifth joint of the peduncle. 



Fig. 10. Serolis exigua, Nordenstam. 

 a, cutting edges of mandible: x 55. b, second thoracic appendage of adult cJ: x 55. c, third thoracic 

 appendage of adult ,^: x 55. d, fourth thoracic appendage: x 55. 



The mandibles are of the ordinary type ; the cutting edges are comparatively simple 

 and of the form shown in Fig. 10 a. 



The outer lobe of the maxillula bears eight spines and one delicate seta on its distal 

 truncate extremity. The inner lobe is about half the length of the outer, with its distal 

 end somewhat expanded and bearing a single, short curved seta with a bifid extremity. 

 There are two pectinate setae on each of the two outer lobes of the maxilla, and eight 

 pectinate and four simple setae on the rounded end of the fixed lobe. 



