68 
Ås it may be seen the agreement is very close. The differ- 
ences are not greater, than that they may be ascribed to indi- 
vidual variations (we must remember, that Kråyer had but two 
specimens, Smith even but one specimen). 
The Zoological Museum in Copenhagen has a very large 
material, towards 1000 specimens of P. tarda Kr., of which the 
greater part has been captured in the Skagerak. To convince myself, 
that there were no specimens of F. princeps Smith in the material, 
that hitherto (by H. J. Hansen in "Ingolf" 1908 and by my- 
self in "Vid. Meddel. Naturh. Foren.” 
Kbhvn. 1909) has been determined as P. 
tarda Kr., I have examined each of 
the specimens, but the result has been 
quite different from what might be 
expected, as will be seen from the 
following. 
SAT E Kemp is right, that a great part 
P.t, P ø of the specimens may be referred to 
Fig. 1. Dorsal view of the one of the two principal forms; but as 
6th abdominal segment of 
Pasiphae tarda and Pasi- 
Pphae princeps. are combined with numerous interme- 
diate links. 
Rostrum varies so much, that it can not be used as a distin- 
guishing character. The best characters are, according to my investi- 
gations, the sixth abdominal segment, the antennal plate and the 
spines of the basis of the second pereiopod; but these spines are 
not to be found in specimens smaller than 25—40 mm., and even 
in larger specimens their number is varying. G.0O.Sars says (1. c. 
1882, p. 48) "the number of spines in the two first pairs of per- 
eiopods is a characteristic too inconstant to be considered as 2 
real specific characteristic'".  Nevertheless we may in most cases 
use the characteristic of Kemp (l. c. 1908 (1910) p. 42—43) to 
separate the two "species” (specimens more than 30—40 mm. long). 
Besides I have found a characteristic, that I have not seen 
my investigations have shown, they 
