Miscellaneous . 
123 
by Sedgwick* for the other Australian species. The feet closely 
agree with those of P. novce-zealandice , as figured by Sedgwick (loc. 
cit .), being provided with a dorso-median papilla above the claws 
and a lateral one on each side. 
Jaws . — The outer blade of the jaw is simple, as in P. novce- 
zealandice, and not provided with an accessory tooth as in P. 
LeucJcartii . 
Genital Aperture . — The genital aperture is situated between the 
legs of the last pair. In some specimens it is a very prominent 
white papilla ; these are probably females. The other specimens, 
in which it is less prominent, may be young females or males, but 
I have found no white papilla on the base of the last leg, such as 
exists in the males of P. LeucJcartii. 
Habitat. — Macedon, Victoria. In and upon rotten wood. 
On the Compound Eyes of Arthropods. 
‘Studies from the Biological Laboratory of Johns Hopkins Uni- 
versity/ vol. iv. no. 6, contains a paper “ On the Morphology of the 
Compound Eyes of Arthropods/’ by Mr. Sho Watase, which is of 
interest owing to its bearing on the origin of the compound eyes of 
insects. 
The principal subject of the paper is the eye of Limulus ; but 
types of the three great groups of Arthropods — Insecta, Crustacea, 
and Arachnids — were studied, and the results are included in the 
generalizations at the close of the paper. 
The primitive type of the ommatidium, or visual unit, is traced 
into a simple open ectodermic pit, from which he believes the com- 
pound eyes of Arthropods to have developed by a vegetative repe- 
tition of similar structures, not unlike what is supposed to have 
taken place in the formation of certain compound organs in other 
animals, such as the kidney in Vertebrates or the respiratory organs 
in Lamellibranchs. 
Taking the number of facets as given by Lubbock, the compound 
eye of the house-fly ( Musca ) would represent about 4000 invagina- 
tions of the skin, and of the dragon-fly ( AEschna ) about 20,000, 
while an ocellus would represent a single pit. 
In an appendix the compound eye of the starfish is briefly con- 
sidered, and is found to be morphologically strikingly similar to that 
of an Arthropod. Six lithographic plates accompany the paper and 
admirably illustrate the author’s studies . — Insect Life , vol. ii. no. 10, 
April 1890, p. 293. 
* u Monograph of the Species and Distribution of the Genus Peripaius 
(Guilding),” Quarterly Journal of Microscopical Science, April 1888. 
