ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
383 
called accessory lens, probably comparable to the pigmented “ clear 
sphere ” in Copilia, and apparently innervated by the optic nerve. 
The pigment not only surrounds the optic rods, but forms partitions 
and tubes in the interior. There are three optic rods, of unequal thick- 
ness, and twisted like a screw round 360°. The pigment-rod itself is 
notched in the middle, and thereabouts the optic nerve enters. 
Gegenbaur compared this remarkable eye to a telescope, and sup- 
posed that rhythmic longitudinal movements of the pigment-rod secured 
accommodation by bringing the crystalline sphere ( SecretJcugel ) nearer 
the cornea. 
Exner fixed his attention on supposed lateral movements of the 
pigment-rods, which he suggested might enable the terminal nervous 
apparatus to sample the image which is formed by the frontal lens, but 
is too large to be appreciated as a whole. But Steuer was unable 
to detect anything but the rhythmic movements of the gut which 
have an influence on the eyes. He cannot accept either Gegenbaur’s 
or Exner’s theory, but refrains from suggesting as yet what his own 
view is. 
The Genus Sympagurus.* — MM. A. Milne-Edwards and E. L. Bou- 
vier discuss this genus, which closely resembles Parapagurus, except that 
the branchial lamellae have become biserial, and the false genital appen- 
dages have a tendency to disappear. Eight species are known, and of 
these a diagnostic table is given. A new species, Sympagurus Grimaldii, 
is described. 
Systematic Notes on Copepods.f — Dr. W. Giesbreclit makes a 
number of corrections and additions. Boeck’s insufficiently described 
Pseudocalanus elongatus is not the same form as that which Brady de- 
scribed by that name ; the latter must be referred to a new genus 
Bradyidius, related to Aetidius. Scott’s Amallophora , proposed as a sub- 
genus of Scolecithrix Brady, belongs to the genus Xantliocalanus Giesbr . ; 
Scott’s Pleuromma princeps belongs to Metridia ; in both these cases the 
specific name must be changed ; and Giesbrecht proposes Scotti. The 
hitherto unknown female of Arietellus setosus Giesbr. is described. Tlio 
form which Scott describes as Labidocera Darwinii Lubbock is a distinct 
species, L. Scotti. As to Scott’s Paracartia spinicaudata and P. dubia , 
they are respectively the female and male of a species of Acartia (A. 
dubia), nearly related to I. C. Thompson’s A. verrucosa. 
New Edriophthalma from Irish Seas.J — Mr. A. O. Walker describes 
Leuconopsis g. n., resembling Leucon in many ways, but distinguished 
as follows. The female has a distinct two-jointed appendage to the 
fourth pair of feet, not furnished with natatory setas ; the lower antennae 
are short, with the third joint conical, with three minute one-jointed 
rudimentary flagella ; the rami of the uropods are subequal ; the male 
has a pair of curved blade-like processes on the second joint of the third 
pair of feet. One species is known, L. ensifer. 
* Bull. Soc. Zool. France, xxii. (1897) pp. 131-6. 
t Zool. Anzeig., xx. (1897) pp. 258-5. 
+ Journ. Linu. Soc. (Zool.), xxvi. (1897) pp. 226-32 (2 pis.). 
2 E 
1897 
