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PACIFIC SCIENCE, Vol. XX, October 1966 
group is very like that of the two species of 
the typica group and may indicate a closer 
relationship to that group than is true for 
robusta and perezi with their strikingly different 
structure of this appendage. In classification of 
all Copepoda, it seems to me that form of 
appendages must be considered along with 
numerical aspects, such as numbers of segments 
and setae. 
Lang (1948) incorrectly ascribed authorship 
of D. fusiformis to Brady and Robertson, 1876, 
a nomen nudum. The species, listed by these 
authors as fonesiella fusiformis, n. gen., n. sp., 
dates from the description by Brady (1880). 
Sars (1909:336) mentions a species D. brucei, 
supposedly described by T. Scott. So far as I 
have been able to ascertain, this is an erroneous 
reference to Cyclops brucei T. Scott. 
the sibirica GROUP 
sibirica group: Lang, 1944, p. 9 (original defi- 
nition) ; 1948, p. 298 (emended def . ; in- 
clusion D. stefanssoni ). 
Lang interprets the stout spinous projection 
of the inner margin of segment 1 of the endo- 
pod of male leg 2 as a transformed seta. 
Whether this process is a modified seta or an 
enlarged projection of the segment itself can be 
determined only by study of developmental 
copepodid stages. Until such information is 
available, it seems best to me to emend the 
definition of the group by referring to this as 
a process or a "projection” of the segment, as 
Sars (1898) has done. 
Danielssenia sibirica Sars 
Danielssenia sibirica Sars, 1898, p. 343, ph 
10, figs. 1-20. 
Danielssenia sibirica: Yashnov, 1935, pp. 
127, 134, fig. 6 (occurrence; notes on 
length; fig. leg 5 $ ). — Lang, 1948, p. 
282, table 5 (leg setation) ; p. 298 (taxo- 
nomic group; key); p. 301, fig. 146.5 
(figs., diagnosis from Sars). — Borutzky, 
1952, p. 105, figs. 37, 38 (description, 
figs, from Sars). 
comments ON literature: Sars has un- 
doubtedly confused female legs 3 and 4. In the 
text, he states they have the same number 
of setae (3) on the inner margin of the endo- 
pod, differing from the male with only 2 setae. 
His Figure 12 is labeled leg 4, but since the 
length of its endopod is similar to that of D. 
stefanssoni shown here (Fig. 2C), it seems 
logical that Sars’s Figure 12 was drawn from 
leg 3, leg 4 being illustrated only for the male 
of sibirica. Lang (1948: Table 5; p. 298) has 
rightfully questioned this setation. Sars also 
found no setae on female exopod segment 1 
of legs 2 and 3 (his leg 4), but illustrated them 
in male legs 3-4. The copy of Sars’s paper used 
in my study is a reprint autographed by Sars as 
a presentation copy to G. S. Brady and now part 
of the library of the Division of Crustacea, 
U. S. National Museum. All of the figures of 
the legs, in which this seta is not clearly 
shown, have indistinct lines where the seta 
should be, if present, suggesting partial erasure 
or inadequate reproduction. Sars (p. 325) ex- 
pressed dissatisfaction with the reproduction of 
his drawings, commenting that "the finer 
shadows in the figures have been to some ex- 
tent lost.” It is possible, therefore, that an inner 
seta is present in both sexes of sibirica on exo- 
pod segment 1 of legs 2—4, as in stefanssoni. 
(See also comments in description of D. 
stefanssoni below.) 
An aesthete occurs on segment 4 of the fe- 
male antennules of both sibirica and stefanssoni, 
and the 5 -segmented antennule of sibirica, if 
correctly depicted, results from fusion of two 
segments of the apical part. This is clearly 
separated into two segments in my specimens of 
D. stefanssoni, resulting in the 6-segmented 
antennule also noted by Willey (see Fig. 1 G 
herein). Other differences that may be real or 
not exist in the numbers of setae of parts of 
the other cephalic appendages, such as the apex 
of the antennal endopod. Sars, like Willey, has 
shown the seta of the end claw of the maxil- 
liped arising near the apex, a probable error by 
both authors (see Fig. 1 E herein). 
It seems to me, in comparing Alaskan speci- 
mens of D. stefanssoni and the original descrip- 
tions of the two species, that they differ very 
little and may actually be separable by fewer 
differences than is apparent in the literature. 
The most reliable distinction seems to be that 
found in the reduced third segment of the 
