956 DR. H. 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.‘ and trl.’ 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 preceding stage; on the abdomen the dorsal 
spines are somewhat reduced and the epimeral spines are lost, but 
the spine on the 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 pre- 
served 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 con- 
verging obtains a considerable breadth with the external margin 
somewhat convex in outline. The ext. br. of urp. becomes pro- 
portionally 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, described by Bate (p. 437), and later on described 
and figured by Ortmann (p. 35, Taf. iii. fig. 2). 
The sub-adult stage of S. mediterraneus, m., is shortly described 
above. The smallest larva of this species known to me is about 
95 mm. long, and this and a specimen a little longer are easily 
distinguished from the similar stage of S. areticus, 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 on its superior margin, the hepatic spine is rudi- 
mentary or wanting; in the antenu. ped. the two distal joints 
together are shorter than the basal one, and this presents a shape 
other than in S. arcticus, 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. arcticus; a 
very short dorsal spine is present on the fourth to sixth abdominal 
segments ; the ext. br. of urp. is proportionally broader than in 
S. arcticus, between 4 and 5, but not 5 times longer than broad. 
As stated above, S. arcticus, Kr., has not been captured outside 
