OCR Text |
Show 1903.] IN THE ‘ CHALLENGER COLLECTION. 55 which is a reduced branchia; these lamellae are very long above t il.2 and trl.3, while the two anterior lamellae above mxp.3 and trl.1 are much less prominent. On mxp.' is found an epipod (ep.), with a branchia consisting of a few plates, and above it a rudimentary pleurobranchia consisting of one very small lamella. Fig. 1 a and fig. 1 c show the rostrum, consisting of a carina with a short or very short terminal spiniform process. There are no supraocular or hepatic spines; the gastro-hepatic groove is well developed. A comparison of fig. 1 c 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 upwards (fig. 1 b ; 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. 1 d). In the antenn. ped. the basal joint is very broad (fig. 1 b), 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. (The specimen from which figs. 1 c and 1 e were drawn measures 51 mm. in length, and was captured on Stat. 146 ; figs. 1 ct-l b were drawn from the specimen secured on Stat. 159). But besides these five specimens of Petalidium, I found still two smaller specimens of the same genus among the ‘ Challenger ' animals. One of these had been determined as Sergestes jciponicus Bate, but is not referred to that species in his text. It was captured at Stat. 158, 7/m., 1874, 1800 fathoms, thus near one of the above-named stations. It measures only 21*5 mm. in length. Figs. 1 /a n d 1 g 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 proportionately 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 branchiae above trl.4 This small specimen belongs certainly to P . foliaceum Bate. Bate established (pp. 428-31) his Sergestes profundus on two specimens, both badly mutilated. He desciibes each specimen separately, beginning with one captured at Stat. 137, lat. 55" 59 S., long. 1° 34' E., depth 2550 fathoms. But, unfortunately, this specimen does not belong to Sergestes but to I etcihdizmz 5 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 a; 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 the crest with a small tooth." The eye-stalks are as in the small specimen from Stat. 158 just |