198 Transactions. — Zoology. 



difference. The epimera, again, though of the same shape as 

 in /. uncjulata. are more or less anchylosed to their respective 

 segments, especially in the second, third, and fourth segments, 

 where the dividing-mark is difficult to be seen ; in the fifth, 

 sixth, and seventh segments the epimera are anchylosed 

 anteriorly, but free behind. The segments are somewhat 

 separated at the sides, so that the lateral borders are not so 

 continuous as in New Zealand specimens of /. uugulata; the 

 terminal notch is deeper, and the postero-lateral angles more 

 rounded and produced. Altogether, the differences between 

 the specimens are pretty considerable ; but, taking into con- 

 sideration the variation known to exist on these points in this 

 and other species, I am inclined to follow Miers in combining 

 the two species. In all respects except those mentioned the 

 resemblance is very close. 



It will be seen that in the coalescence of the epimera with 

 their segments, and of the segments of the postabdomen, and 

 in the rounded postero-lateral angles, the Australian specimens 

 resemble I. elonrjata, and tend to connect that species with 

 /. uugulata. 



Idotea elongata. 



Idotea elongata, Miers, "Jour. Linn. Soc," xvi., p. 54 

 (1881) ; " Cat. N.Z. Crust.," p. 93, pi. ii., fig. 3 (1876) : Chilton, 

 " N.Z. Journal of Science," vol. i., p. 517 (1883) : Thomson, 

 "N.Z. Journal of Science," vol. i., p. 332 (1883) : Thomson 

 and Chilton, " Trans. N.Z. Inst.," xviii., p. 156 (1886). 



2 Eclotia dllatata, Thomson, "T'rans. N.Z. Inst.," xvi., 

 p. 235, pi. xii. (1884); Thomson and Chilton, "Trans. N.Z. 

 Inst.," xviii., p. 156 (1886). 



"Body elongate, almost linear, smooth, with the dorsal 

 surface very convex, so that the animal appears almost cylin- 

 drical in a dorsal view. Head with the anterior margin 

 scarcely excavated, but with a slight depression in the middle 

 between the antennules ; antero-lateral angles not prominent. 

 Segments of the thorax (in the adult male) usually longer than 

 broad, first segment with the antero-lateral lobes prominent 

 and obliquely truncated. Postabdomen about equalling the 

 3i posterior thoracic segments in length, having usually in- 

 dications of a lateral suture on each side at some distance 

 from the base of the terminal segment, which is rather de- 

 pressed above, with subparallel sides, rounded postero-lateral 

 lobes, and a moderately deep rounded notch at its distal end. 

 Eyes small. Antennules scarcely reaching to the distal end 

 of"^ the antepenultimate joint of the antennae, wdiich have a 

 short peduncle, the last two joints of which are subequal, and 

 each but little longer than the antepenultimate joint ; flagellum 

 18-22-jointed ; when retracted the antennae do not reach 



