716 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Coleoptera, a result which seems to be confirmed by the habits of the two 
groups and their order of appearance in time. 
Development of Embryo of Locustidae.* — Mr. W. M. Wheeler has a 
preliminary notice of the development of Xiphidium ensiferum. The 
eggs are laid under the scales of galls produced by Cecidomyia salicis- 
gnaphaloides. They are about 5 mm. long and are slightly curved, 
the convex side being the ventral and the sharper end the cephalic part 
of the egg. The author states that this differentiation in the form of 
the egg is of great importance for a correct understanding of its develop- 
ment. The small ventral plate is formed by the parting of the blasto- 
derm cells in the middle of the convex side of the yolk. The very 
delicate gastrula-groove soon becomes apparent, and at the same time a 
rounded cellular disc is seen in the middle line in front of the cephalic 
lobes. This disc is called by the author the preoral plate, and it arises as 
an independent and isolated centre from the blastoderm by the conversion 
of a number of flattened cells into closely packed columnar and spindle- 
shaped elements. The organ does not, therefore, differ from the ventral 
plate in its mode of origin. 
The preoral plate seems to early lose its independence, as it becomes 
connected with the head of the embryo ; it comes to lie between the two 
cephalic plates. When the embryonic coverings are formed the plate is 
shut out, although the two cephalic lobes are included in the process. 
The author describes the successive stages of development ; at last 
the yolk is found to be surrounded by chorion, yolk-membrane, primary 
serosa, secondary serosa, secreted layer, cuticle, tertiary serosa, and 
amnion ; later on a larval membrane is added. 
The author has not been able to find any description of an organ 
which can be thought to agree with the preoral plate of Xiphidium , 
but the Crustacea, and especially the Isopoda, have in the dorsal organ 
a structure which has a certain similarity to this peculiar embryonic 
organ. If we go beyond the Arthropoda we find in the prestomium of 
Annelids an organ which at first sight has a resemblance to the preoral 
plate ; but when the whole development of the structure is studied not 
much support is to be found for such a view. It is possible that in other 
Locustidae the organ will be discovered to be more completely retained 
than in Xiphidium. 
Leaf-winged Locust, j* — Mr. J. J. Quelch describes some remarkable 
cases of protective colouring in Pterochroza and allied forms. The 
wings are ovate and one side is somewhat wider than the other, according 
to the depth of the curve of the central vein which is thickened like a 
mid-rib. From this pass off side veins which branch and reticulate just 
as in the case of the leaf of a dicotyledonous plant. In one species the 
shade varies from reddish brown or yellow to a dull purple, and closely 
resembles the shades to be found on the young leaves of many of the 
forest trees, and more especially of Mora excelsa. In another the tint is 
deep green, but seems to fade on continued exposurs to light after the death 
of the insect. In a third it is of a very pale yellowish brown, much like 
* Zool. Anzeig., xiii. (1890) pp. 475-80. 
f Journ. Roy. Agricult. Soc. Brit. Guiana, 1890, p. 141. Ann. and Mag. Nat. 
Hist., vi. (1890) p. 275. 
