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Show 956 DR. 11. J. HANSEN ON CRUSTACEANS [Dec. 1, reach to the middle of the second joint of the antenn. ped.; the basal joint of this peduncle is to the two following together as 11 to 8 ; trl.4 and trl.5 are only buds. The first and second abdominal segments each with a short dorsal spine, the third to sixth segments each with a long spine; the first segment a little above the middle of each side with a rather short spine directed outwards, and besides the epimera of the five anterior segments each produced into a rather long spine, which is directed outwards and on the two anterior segments even bent somewhat upwards and forwards ; the sixth segment below on the posterior edge with a shorter spine. The ext. br. of urp. is about 8 times longer than broad, and the spine a little beyond the middle of its exterior margin. Telson with a long process from each of its posterior edges. The following stage is that described by Kroyer : the rostrum is as already mentioned, the hepatic spine has become somewhat shorter than in the precediug stage ; on the abdomen the dorsal spines are somewhat reduced and the epimeral spines are lost, but the spine on tbe side of the first segment is still visible. During the subsequent stages a series of alterations take place. The rostrum becomes shortened, but is, however, still during a longer period more than half as long as the eye-stalks, its dorsal spine and the hepatic spines are considerably shortened, the eye-stalks become somewhat shorter; the median protuberance is preserved during some time; the abdominal spines soon completely disappear. In the antenn. ped. the two distal joints together successively are approaching the length of the basal joint, which from being distally slender with the lateral margins slightly converging obtains a considerable breadth with the external margin somewhat convex in outline. The ext. br. of urp. becomes proportionally broader and the spine more remote from the middle of the exterior margin; the process from the edge of the telson becomes shorter and finally disappears. One of these stages is S. dissimilis, Bate, describee! by Bate (p. 437), and later on described and figured by Ortmann (p. 35, Taf. iii. fig. 2). Tbe sub-adult stage of S. mediterraneus, m., is shortly described above. The smallest larva of this species known to m e is about 9*5 m m . long, and this and a specimen a little longer are easily distinguished from the similar stage of S. arctlcus, Kr. The eye-stalks are somewhat shorter; the rostrum is rather short, not half the length or about one-third of the length of the eye-stalks, with a trace of a spine ou its superior margin, the hepatic spine is rudimentary or wanting; in the antenn. ped. the two distal joints together are shorter than the basal one, and this presents a shape other than in S. arctlcus, as in its distal half the lateral margins are parallel with each other; and this part is scarcely broader than the two distal joints, which are obviously coarser than in S. arctlcus; a very short dorsal spine is present on the fourth to sixth abdominal segments; tbe ext. br. of urp. is proportionally broader than in S. arctlcus, between 4 and 5, but not 5 times longer than broad. As stated above, S. arcticus, Kr., bas not been captured outside |