TANAIDACEA AND MARINE ISOPODA FROM JUAN FERNANDEZ 547 



Distribution: Portugal, Florida, Cape of Good Hope. 



The specimens differ from the figure of Aega Webbi (cf. SchiOdte and 

 Meinert 1879, Tab. X, fig. 4) in not having the 5 »spines» on the merus of 

 the first 3 pereiopods placed at equal distances, but in two different groups at 

 some distance from each other; one group, consisting of a longitudinal row of 

 3 spines, is placed more proximally, the other two spines are situated more 

 distally. I cannot regard this difference as very essential. At the most it 

 might be considered as being of varietal value. 



Aega bicavata n. sp, — PI. 20, fig, 11; text fig. 11. 



One male specimen, length 41 mm. 



Loc. Juan Fernandez, Masatierra. On a fish, (»bacalao»), Polyprion 

 prognatus Forster? Taken together with one specimen of Aega Webbi. 



Description. 



Head. The frontal margin concave on each side; the median elongation 

 acute, reaching to about the middle of the internal margin of the first joint 

 of the antennulae. The eyes are ovate and grayish, twice as long as they 

 are broad, rather near each other, the shortest distance between them being 

 only about 74 — Vs ^^ their greatest diameter and as long as half the length of 

 the basal joint of the antennulae. 



Lamina-frontalis (fig. 1 1 a) subquadratic, slightly widening anteriorly and 

 with a slight lateral carina on each side; the anterio-lateral corners rounded, front 

 margin slightly convex and with a small tip between the bases of the antennae. 



Thorax. The ist, 5th and 6th segments subequal in length, the 6th 

 slightly longer. The 2nd segment about % the length of the ist; 2nd to 4th 

 segments increasing slightly in length. Anterior margin of ist segment bi- 

 sinuated. Posterio- lateral angle of the ist segment acute and a little produced, 

 lateral margins with a carina. 



Coxal plates of the two following segments subrectangular with the 

 posterio-lateral angle produced and acute, and the hinder margin a little sinuous 

 near the apex. They are transversed by a lateral carina. The last 4 seg- 

 ments with posterior corner of the coxal plates considerably produced and acute, 

 transversed by one diagonal lateral carina and one on the ventrolateral border. 



Abdomen. Seen from above, the first segment is partly covered, a little 

 broader than the 4th. The 6th abdominal segment anteriorly about 3 limes 

 broader than posteriorly. Anterior margin straight, lateral margins slightly 

 convex, posterior margin emarginate, dorsal surface on each side near the 

 basal joints of the uropods with one faint hollow. 



Colour pale yellow, on the 4th — 7th thoracic segments a little grayish 

 with rounded paler spots. 



Antennulae reaching to about ^3 ^^ the length of the 5th joint of antennae 

 and not quite reaching the anterior angle of first thoracic segment. The 

 peduncle is about twice as long as the flagellum. ist joint of peduncle about 

 as long as it is broad with the anterio-distal corner about right-angled, some- 



