380 



Idotea Basteri. AUDOUIN, Descr. of SAVIGNY, Egypt. Crust, pi. 12, 



f. 6. Roux, Crust. Mediterr. t. 29, f. 110. 



Idotea tridentata. LATREILLE, Con. Crust, et Ins. 1, p. 64. LAMARCK, 



H. Anira. s. Vert. 5, p. 269. 



Idotea varieyata. Roux, Crust. Mediterr. pi. 30, fig. 1 9. 



Armida bimaryinata. Risso, H. n. Eur. merid. 5, 109. 



THIS large species has the body of a very elongate- 

 oval form, slightly narrowed towards the extremity of 

 the tail, which is terminated by a strong central point, 

 having a smaller one on either side, which is, however, 

 often wanting, and the lateral angles rounded. 



The lower antennae are nearly half the length of the 

 entire animal, the first joint very short and scarcely 

 visible from above; the four following joints gradually 

 increase in length, but decrease in thickness, and the 

 flagellum, which is rather longer than the five-jointed 

 peduncle, is slender, and consists of about twenty articu- 

 lations. The first segment of the body has the coxal 

 plate fused at the sides, but the six following have it 

 separated by a curved incision (indicating the epimeral 

 or basal joint of the legs), and which is more angulated 

 in the middle on the three posterior segments. The 

 anterior segment of the tail in the male is armed beneath 

 with two short horny points, directed backwards, and the 

 second pair of the branchial plates is also furnished, in 

 this sex (at least), with an elongated style, nearly as long 

 as the plates. 



The tail consists, apparently, of four segments, of 

 which the first and second are quite distinct, although 

 very short, but the third loses all trace of articulation 

 in the middle of the back, so as to appear completely 

 soldered with the large terminal joint. 



This species varies greatly in its colours and markings ; 

 generally, it is of a dirty greenish-grey, but often has a 

 pale longitudinal line down the middle of the back, or 



