OCR Text |
Show 946 DR. H. J. HANSEN ON CRUSTACEANS [Dec. 1, iv. Synonymlcal and other Remarks. Before proceeding to a systematic arrangement, founded upon the characters mentioned, it will perhaps be convenient to undertake some reduction of the species, especially of the adult forms, with a view to freeing the next chapter, containing notes on the structure of the species and their larvae, from these disturbing investigations. The single species established by de Natale, S. arachnlpodus (p. 19, Tav. ii. fig. 1), is quite unrecognizable to me, and will, in my opinion, never be interpreted with certainty; therefore I have omitted it from the systematic arrangement. Of the 15 species described by Kroyer, only 4 (S. fiisll, Kr., S. arctlcus, Kr., S. cornutus, Kr., S. edwardsi, Kr.) have been established upon adult animals. Bate, Chun, and Ortmann have already considered S. frisll, Kr., to be identical with S. atlanticus, M.-Edw., but when Bate (op. cit} p. 389) furthermore withdraws S. arctlcus, Kr., this is, as pointed out by Ortmann, quite wrong. Of the remaining 11 species 8 are true Sergestes-larvft, while the 3 others, viz. S. obesus, Kr., S. caudatus, Kr., and S. serrulatus, Kr., must be removed from the genus. S. obesus, Kr. (p. 257, tab. iv. fig. 10, a-f) is a very curious form ; the single Krbyerian specimen had been dissected and most of the pieces are preserved, but an investigation of the type specimens of S. sanguineus, Chun (1889), proved that this form is identical and that both species have been established upon larvae which differ so much from the Mastigopus of Sergestes that the species must be removed from this genus, and it will be discussed later on under Petalldlum, Bate. S. caudatus, Kr. (p. 270, tab. v. fig. 14, a-d), is a very young Penceus that has just passed the Mysls-stage (Kroyer's representation of the trunk-legs is not correct, as his type specimen possesses a well-developed chela on trl.1, behind which pair are found the basal joints of 4 pairs). S. serrulatus, Kr. (p. 268, tab. iv. fig. 12, a-g) is a very young Acetes, M.-Edw. Finally, S. laciniatus, Kr. (p. 274, tab. v. fig. 15, a-e), is, as already pointed out by Ortmann, identical with S. corniculum, Kr. Of the species described by Stimpson only one is adult, viz. S. paclficus, Stimps. (p. 45), and it is, in m y opinion, identical with S. atlanticus, M.-Edw., as the differences which the author states to exist between his species and Kroyer's description of S. frisll, Kr., are of no value. The fact is that the hepatic spine is placed a little more behind than in Kroyer's figure, in which also the trunk-legs are delineated a little shorter than they are in the animals. Of the other species, S. longicaudatus, Stimps., and Sergia remipes, Stimps. (p. 46), can, in my opinion, scarcely be recognized without examination of the type specimens. Of Serg. meyerl, Metzger (p. 302, 'tab. vi. fig. 7), I have 1 I always quote the ' Challenger ' Report, not his preliminary Kroyer, I refer to his monograph, omitting his earlier descriptions without figurea. |