264 A HISTORY OF RECENT CRUSTACEA 
among preserved specimens of Euphausiidee. The two coni- 
cal ovisacs, placed side by side between the last two pairs 
of appendages of the trunk, ‘do not consist of incubatory 
lamellee, as in other Schizopoda, but merely of an exceed- 
ingly thin membrane, derived, it would seem, from some 
glutinous fluid issuing along with the ova and coagulated 
by the action of the sea-water as a delicate envelope sur- 
rounding aud keeping the ova together during the em- 
bryonal development.’ The curious fact is noticed that of 
the northern species the specimen of Nyctiphanes Couchiw 
figured by Bell in his ‘ History of British Crustacea’ is the 
only ovigerous one that has as yet been recorded. 
Benthewphausia, Sars, 1885, has all the legs distinctly 
developed, and though the last pair are rather short, they 
have both branches of a structure similar to that of the 
preceding pairs. The single species, Bentheuphausia 
amblyops, Sars, has small and imperfectly developed eyes. 
The three specimens on which it was founded were taken 
from depths between 1,000 and 1,800 fathoms, and appear 
to be devoid of the luminous globules found in so many 
other members of this family. 
Thysanoessa, Brandt, 1851, has the last pair of legs quite 
rudimentary, and the preceding pair exceedingly small, 
devoid of the three terminal joints. On the other hand, 
the second maxillipeds are very elongate, much longer 
than the following legs. They have the last two joints 
armed with spiniform bristles on both margins. ‘The 
eyes in this genus are of a somewhat irregular form, with 
the cornea divided, as it were, into two compartments by 
a transverse constriction. The type species, Tysanoessa 
longipes, Brandt, from the Siberian Sea, is identified by 
Norman with the earlier Thysanopoda neglecta, Kroyer. 
Sars has added a southern species, Thysanoessa macrura ; 
a wide-ranging species, T'hysanoessa gregaria, which is found 
in the Mediterranean ; and two from the coast of Norway, 
which he has named borealis and tenera. Dr. H. J. Hansen, 
however, having examined Kréyer’s specimens in the Co- 
penhagen Museum, has come to the conclusion that 
Thysanoessa borealis, Sars, should be called Thysanoessa 
