328 SUMMARY OF CURRENT RESEARCHES RELATING TO 
the right than on the left, in . proportions which vary with different 
localities ; in the males the eye appears to be always on the left side. 
In P. gracile the eye is always on the right side, in both sexes. 
P. xiphias seems to follow the same rules as P. abdominale. Unlike 
Dr. Brady, the author has not found one Pleuromma without a lateral 
eye. 
In minute structure this organ does not resemble the unpaired or 
median eye which is so common in Copepoda. The projection which 
forms the organ is constituted by the continuation of the cuticle, has a 
black ring at its base, and has the convex part almost colourless. The 
chitin is very fragile ; below the swollen portion of the cuticle there is 
a small, more or less spherical mass, which appears to be formed of a 
considerable number of more or less spherical bodies. In the not very 
well preserved specimens at his disposal, the author was unable to 
establish the presence of a nerve, and, indeed, for further details a 
supply of fresh specimens is needed. 
Lateral Organ of Pleuromma.* * * § — Dr. F. Dahl divides the species of 
Pleuromma into three groups : — (a) P. gracile and P. boreale sp. n. ; 
(6) P. abdominale and P. xiphias ; (c) P. robustum sp. n. and P. quad- 
rangulatum sp. n. He states their specific diagnoses and geographical 
distribution. He believes that the lateral organ is luminous and not 
optic, on account of its unilateral position, its histological structure, and 
its resemblance with the luminous organ of Euphausia. Among Cope- 
pods luminosity and the possession of a lateral organ go together, 
though perhaps not constantly. 
Commensals of Mediterranean Turtles.j — MM. E. Chevreux and 
J. de Guerne have a note on the Crustacea found commensal on Thalasso- 
chelys caretta ; Hyale Grimaldi , Platophium chelonophilum , numerous ex- 
amples of Caprella acutifrons , Tanais Gavolinii , Lepas Hilli , and Concho- 
derma virgatum are reported. Platylepas bissexlobata , found in 1832 on 
Mediterranean Turtles, does not appear to have been seen again. 
New Caligidae.J — Prof. P. J. Van Beneden gives an account of some 
new species of these parasitic Copepods from Africa and the Azores. 
What most struck the author was the extraordinary abundance of com- 
mensals of inferior rank which were found on these parasites themselves. 
Some were literally covered by Campanulariae, Acinetae, or Podophrya. 
A proof of how rapidly the surface of the body is invaded is shown by 
the fact that the ovisacs even were covered before the eggs had escaped. 
The new forms are called Caligus Dakari , Nogagus angustatus , Calina 
brachyura , Pupulina Flores , and Galigera difficilis. 
Daphnia.§ — Prof. V. Capanni has published a study of Daphnia 
pulex , telling in a frank way what he has observed under his Microscope 
as to the structure and life of this familiar Crustacean. The booklet, 
although accompanied by a bad figure of the animal, may be of use in 
inducing students to share the author’s joys of observation. 
* Zool. Anzeig., xvi. (1893) pp. 104-9. 
t Comptes Rendus, cxvi. (1893) pp. 443-5. 
X Bull. Ac. Roy. Belg., lxii. (1892) pp. 241-62 (4 pis.). 
§ ‘ La Dafnia,’ Reggio Emilia, Tip. Artigianelli, 1892, 8vo, 24 pp., 1 fig. 
