TANAIDACEA AND MARINE ISOPODA FROM JAUN FERNANDEZ 53 1 



Abdomen a little shorter than the last two thoracic segments. The 

 first 3 abdominal segments decrease in length from the ist to the 3rd; together 

 they are of the same length as the 7th +c. Ya of the 6th thoracic segment. 

 Their lateral margins are provided with a row of setae. The 3 posterior seg- 

 ments are about 7$ ^^ broad as the 3rd segment. The last segment has its 

 posterior margin evenly rounded and is about as long as the 4th and 5th 

 together. 



Colour pale yellow, with the whole carapax, or only the anterior part, 

 brownish marmorated; sometimes there are marmorated spots also on thorax 

 and abdomen. 



Antenniilae about as long as carapax. The ist joint a little longer than 

 the 2nd and 3rd together, the 2nd joint a little longer than half the ist, the 

 3rd narrower and shorter than the 2nd. The flagellum of one short joint. 

 The relation between the lengths of the joints is: 55:29:19:4. 



Antennae (fig. 3 a) a little shorter than the antennulae. They reach to 

 about the proximal margin of the 3rd joint of the antennulae. The 1st joint 

 almost as long as the 3rd. The 2nd joint broader but a little shorter than 

 the 4th. Flagellum of 2 small joints, the last minute. 



Mandibles (fig. 3 b). Apex bluntly pointed, almost rounded. Lacinia mo- 

 bilis on the left mandible conical. The molar tubercle cylindrical, distally with 

 a circle of dents. 



ist maxillae (fig. 3 c). The palp consists of 2 joints, of which the 2nd 

 has 2 apical setae. 



2nd maxillae small, ovate, with distal end broadly rounded. 



Maxillipeds (fig. 3 d). The last joint on the outer distal margin with a 

 characteristically small incision, in which a group of setae are situated. 



Chelipeds (fig. 3 e) are similar in every detail in males and females. They 

 are directed straight ventrally, so that in the dorsal view no trace of them can 

 generally be seen in the males, and very little in the narrower females. Carpus 

 is more than i 72 times the breadth. Propodus about twice as long as it is broad. 

 The base of the immovable finger about twice as broad as the dactylus, its 

 lower margin with 5 setae. The free distal margin of propodus slightly con- 

 vex, with a row of 7 setae. 



2nd — 'jth pereiopods. The small ischial joint was not distinguishable. 



2nd pereiopods (fig. 4 a). The 6th joint 7; longer than the 4th and 5th 

 together. These together are slightly longer than the last joint with claw. 



^rd pereiopods (fig. 4 b). Propodus 72 shorter than merus + carpus. Carpus 

 at the distal margin with 3 broad setae; on the anterior side there are 2 setae, 

 one very strong at the upper distal angle and one submarginal near the lower 

 margin (invisible in the figure); on the posterior side there is one broad seta 

 at the lower distal angle. For other details see the figure. 



The setae are exactly the same in the males as in the females. 



4.th and §th pereiopods. Merus as in the 3rd pair, with a short and broad 

 seta near the lower distal angle. Carpus distally with a circle of 7 broad 

 setae. In the 4th pair the seta at the upper distal angle is much the longest. 



Setae in males the same as in the females. 



^th — Jth pereiopods (fig. 4 c). Carpal joint slightly shorter than the merus 



