1896.] OF THE GENUS SERGESTES. 947 
examined the type specimen and must declare it to be a large 
female of S. arcticus, Kr. Sp. Bate has in all established 24 new 
species of Sergestes, of which but 3, S. prehensilis, Bate, 
S. japonicus, Bate, and S. kroyert, Bate (all briefly characterized in 
1881), are decidedly adults. Ofthe other species, S. longicollus, Bate 
(p. 421, pl. Ixxvii. fig. 1), at least has almost arrived at the shape 
of the adult, but it is, as pointed out by Ortmann, synonymous 
with S. tenuiremis, Kr. It is impossible to me to form any idea 
of S. profundus, Bate (p. 428); Bate’s specimens were very much 
mutilated. The other 19 species and Sciacaris telsonis, Bate 
(p. 438, pl. Ixxviii. fig. 1), are all Mastigopus-forms in very different 
stages of development.—When Bate (p. 393, pl. Ixviii.) describes 
and figures trl.* and trl.’ in S. atlanticus, M.-Edw., as very short, 
this must, in my opinion, arise from an anomaly or from some other 
reason of no value, if the described and tigured specimen really 
belongs to this species, for I am not convinced that all the specimens 
from the localities enumerated (p. 390) belong te S. atlanticus. He 
states that a specimen, 50 mm. in length, was taken “off Japan ; 
depth 345 fathoms,” and that 3 specimens, 43 mm. long, were 
trawled “south of Australia; depth 2150 fathoms.” ‘hese 4 
specimens at least must be re-examined, as among some hundred 
specimens I have not found one exceeding 30 mm., and the 
localities also make the determination somewhat doubtful. The 
specimens of S. edwardsi, Kr. (Bate, p. 403), must also be 
re-examined with the aid of my descriptions of hitherto not 
recognized allied species. 
S. mollis, Smith, established by that author in 1884 (Rep. Comm. 
Fish and Fisheries, pt. x. p. 419), I consider to be identical with 
S. japonicus, Bate (described 1881), with which it agrees in the 
smallness of the eyes, the relative length and thickness of the joints 
in the antenn. ped., the shape of the squama, the soft and 
membranous integuments, and the number and the feeble 
development of the posterior branchie. 
S. magnificus, Chun, established in 1888 (p. 33, Taf. iv. fie. 4 u. 
5), 1s, according to my examination of one of the type specimens, 
identical with S. arcticus, Kr. Kroyer also has stated that the 
flagellum of the antenne surpasses the total length of the animal 
about 3 times.—S. sanguineus, Chun, established in 1889 (p. 538, 
Taf. ili. fig. 1), is, as stated above, identical with S. obesus, Kr., 
and will be discussed later on under Petalidium. 
In 1891 Wood-Mason (Ann. & Mag. Nat. Hist. 6th ser. vol. viii. 
-p. 354) established S. rubroguttatus, W.-M., a species closely allied 
to S. arcticus, Kr., but the differences in the ext. br. of urp. 
pointed out by the author are certainly valid specific characters. 
.For the rest, I believe that it may be possible to detect more 
characters. Perhaps the species is identical with S. kroyeri, Bate, 
established 1881, but both species being insufficiently described, 
I cannot settle the question, and therefore must support both 
species. 
vot the species established by W. Faxon in 1893, S. halia, Fax. 
