PACKARD.] PHYLLOPODS OF NORTH AMERICA. 331 
they are not varietal. It appears, then, that we have but one North 
American species of Artemia so far as yet known. 
Upon comparing our species with the European it is difficult to find 
good differential characters, as the portions of the body where specific 
differences would be expected to occur are liable to considerable varia- 
tion. Upon comparing a number of females from Great Salt Lake 
with a number of females of the maleless generation from Trieste, Aus- ' 
tria, received from Professor Siebold, there are really no differences of 
‘importance; our A. gracilis (Verrill’s fer- 
tilis) is Slighter, with a smaller head, and 
perhaps the 2d antenne are a little 
slighter in build; I see no essential differ- 
ence in the form of the ovisac, while the 
shape of the legs, especially the 6th en- 
dites, is essentially the same. The length 
of females (as well as males) is the same 
in both species. 
Upon comparing a good many males 
from Great Salt Lake with several, both 
stained with carmine and unstained, re- 
ceived from Cagliari, Sardinia, through 
Prof. J. McLeod, of Ghent, the European 
A. salina is seen to be considerably 
stouter, the head wider, the eve-stalks 
longer and larger, and the eyes larger; 
the frontal button-like processes of the 
first joint of the claspers are nearly twice 
as large as in the American species, and 
a little more pointed, while the claspers 
themselves are larger and stouter. The f 
legs and sixth endites are of about the : 
same form. The most apparent differ- Fic. 18.—Artemia gracilis, from New 
ence is in the caudal appendages or cer- Havenyscon from heneath, much entree 
copods, which in A. salina are several ont', 2d antenne; md, mandibles; mz, max- 
S : ans > - ill; pes, foot; 0, ovisac. 
times larger than in A. gracilis, being in 
the Sardinian specimens nearly three times as long and much larger 
than in our species. In this respect the genus shows a close affinity 
to Branchinecta. However, in a lot of A. salina 2 from Trieste, the cer- 
copods are very much shorter than in the Sardinian females, and only 
a little longer than in our American specimens. These appendages do 
not differ in the two sexes. 
As regards the genus in Europe, several nominal species have been 
described, but it seems probable that but one occurs there. As stated 
by Verrill in his “Observations on Phyllopod Crustacea,” in a foot-note, 
owing to differences in the development of the caudal lobes and sete, 
‘several nominal European species, established mainly on differences 
in the caudal lobes and sete, are probably only the young of others, or 
all perhaps of A. salina, especially since those with small, caudal lobes 
and few or no sete, are described as small; as for example A. milhausenit, 
A. arietina, and A. képpeniana (Fischer species).” 
Verrill’s types of A. monica I have not examined, but have certainly 
found specimens at Great Salt Lake which agree with his description, 
and especially his figures of the head and male claspers. 
Variations in Artemia fertilis from Salt Lake-—With specimens of the 
sexually mature males from Great Salt Lake the description of Verrill 
agrees well, the claspers being very broad, the second joint being as 
