1903.] IN THE ‘CHALLENGER COLLECTION. 55 
which is a reduced branchia; these lamelle are very long above 
trl.? and trl.*, while the two anterior lamelle above mxp.’ and 
trl.‘ are much less prominent. On mxp.” is found an epipod (ep.), 
with a branchia consisting of a few plates, and above it a rudi- 
mentary pleurobranchia consisting of one very small lamella. 
Fig. la and fig. le show the rostrum, consisting of a carina 
with a short or ve1 ‘y short terminal spiniform process. There are 
no supraocular or hepatic spines; the gastro-hepatic groove is 
well developed. A comparison of fig. 1 ¢ with fig. 1 d shows that 
the eye-stalks are considerably depressed; they are from two and 
a half to nearly three times longer than the eyes at the inner 
terminal angle, with a small rounded knot turning inwards and 
a little wpwards (fig. 1 6; fig. 1 d), and besides (always ?) with an 
exceedingly small tubercle somewhat in front of the inner angle 
and more downwards on the inner side (fig. 1d). In the antenn. 
ped. the basal joint is very broad (fig. 1 6), decidedly shorter than 
the outer margin of the two other joints together ; the third joint 
is scarcely three times longer than broad, considerably longer 
than the outer margin and a little shorter than the inner margin 
of the second joint, which is stout, with its Inner margin only a 
little more than twice as long as its breadth. (lee specimen 
from which figs. 1¢ and le were drawn measures 51 mm. in 
length, and was captured on Stat. 146; figs. 1 a-16 were drawn 
from the specimen secured on Stat. 159). 
But besides these five specimens of Petalidiwm, I found still 
two smaller specimens of the same genus among the ‘ Challenger’ 
animals. One of these had been determined as Sergestes japonicus 
Bate, but is not referred to that species in his text. It was 
captured at Stat. 158, 7/111., 1874, 1800 fathoms, thus near one 
of the above-named stations. It measures only 21°5 mm. in 
length. Figs. 1fand 1g show that its rostrum has the terminal 
process somewhat longer than in the large specimens; the eyes 
are a little longer as compared with the length of their stalks, and 
these are pro portionately somewhat broader, without a distinct 
knot at the end of the inner margin. There is no supra-ocular 
spine, but the hepatic spine is moderately developed ; the gastro- 
hepatic groove is very distinct. No branchiew above trl.” This 
small specimen belongs certainly to P. foliaceum Bate. 
Bate established (pp. 428-31) his Sergestes profundus on two 
specimens, both badly mutilated. He describes each Bpeinen 
separately, beginning with one captured at Stat. 137, lat. 35° 59'S., 
long. 1° 34' E., depth 2550 fathoms. But, unfortunately, ne 
specimen does not belong to Sergestes but to Petalidiwm; the 
type is besides so mutilated that I should have preferred to 
omit it, if it had not been described by Bate. It measures 
17-5 mm. in length. The rostrum is shown in fig. 2@; it is 
described by Bate: ‘“ It consists of a short fine point projecting 
horizontally for about one-fourth the length of the ophthalmopod, 
and is dorsally furnished on ihe crest with a small tooth.” The 
eye-stalks are aS in the small specimen from Stat, 158 just 
