182 General Nous. 
Clarke's observations, the visual area is increased in the trilobites 
and that shown by Mr. Watase's unpublished observations on the 
eyes of Limulus.) After maturity, although the trilobite may con. 
tinue to increase in size, senility begins and with it there is a decrease 
in the number of optical elements. 
In a concluding note Mr. Clarke calls attention to the fact that 
in the Leptostracan genus Mesothyra of the Portage (Devonian) 
group " the eye consists of a single deep pit at the summit of the 
optic node." 
The Sexes of Mvxine.— Dr. Fridtjof Nansen (Bergens Mu- 
seum's Aarsberetntng, 1887) states that in his studies of the nervous 
system of Myxine he was struck by the fact that it semed as if females 
only came under review. He therefore investigated the subject, and 
after reviewing the more prominent papers and detailing his own 
investigations states his conclusions that '' Myxine is generally or 
always (?), in its young state, a male; whilst at a more advanced stage 
it becomes transformed into a female." The genital organs are 
female in front and male behind. Nansen has investigated the 
spermatogenesis but his results are widely at variance with those of 
Cunningham. He has also tried, but in vain, to obtain the embryol- 
ogy of this form. Myxine is extremely abundant at Bergen, but 
dredging in the harbor at all seasons of the year has failed to pro- 
duce a single ovum. He has tried to breed them in confinement 
but though gravid females were kept in wooden cages for half a year 
they obstinately refused to lay their eggs. From his studies of 
ovaries he concluded that eggs were deposited at all seasons of the 
year, and he adds to our knowledge of specimens of the eggs of 
Myxine by recording one dredged in 1857 by Dr. Danielssen and 
his son near Molde. Nansen does not seem to be familiar with a 
of 
Zoological News. — Protozoa. — Mr. Beddard, in his earth- 
worm studies, has recently met (Proc. Zool. Soc, London, 1888, p. 
355) ^ gregarine in the body cavity of a New Zealand Perichseta 
which is remarkable among gregarines in forming a nucleated cyst. 
Dr. L. Plate {Zool. Jahrbuck, III., 1888) describes under 'the 
name Acinetoides a new infusorian, of which two species were found 
at Naples, which seems to connect the Acinetae and Ciliata. It 
bears a clubbed suctorial thread for taking food, which is shorter 
and stiffer than those in the true Acinete ; and it possesses besides 
longitudinal rows of cilia on the ventral surface. Acinetoides forms 
colonies and has been seen to divide transversely. 
CcELENTERATA. — Gireg describes and figures as new (Bergens 
Museum's Aarsberetntng for 1887) Rhizoxenia alba and Sympodium 
margaritaceum from the Norv/egian coast. 
