48 Annals Entomological Society of America __[Vol. VII, 
the following means: A small paper receptacle was half 
filled with melted 55% paraffine and allowed to cool consider- 
ably. The insect was then taken up in melted paraffine in 
a warm pipette, and dropped into the receptacle, which was 
then filled. The specimen was then moved into desired position 
with a warmed needle. After following this method of embed- 
ding, little trouble was experienced in trimming up the block, 
and the cutting could be done with accuracy in the plane 
wished. 
Necessary care must, of course, be taken in seeing that all 
material is thoroughly embedded or the sections are very 
liable to tear when the knife comes in contact with the tough, 
chitinous covering of the insect. This chitin was found to 
be extremely impenetrable, and all attempts at staining im 
toto proved futile, though specimens were allowed to stay 
in the staining fluid for days. 
This paper was prepared in the Entomological Laboratory 
of Stanford University, under the direction of Professor V. 
L. Kellogg. I am indebted also to Professor Harold Heath 
for suggestions during the work. 
NERVOUS SYSTEM. 
The nervous system (Plate XII, Fig. 4) of the Coccide 
seems to vary little in structural characteristics in the many 
widely differing groups of the family. The central system 
consists of a fused, bi-lobed cephalic ganglion forming the 
brain, and a prominent compressed thoracic ganglion from 
‘which four pairs of lateral nerves are given off. The posterior 
pair curve out towards the lateral margins of the insect and then 
curve back again apparently fusing or at least giving off a 
great number of smaller nerves which form a delicate fan-shaped 
nerve center in the pygidium. The circum-oesophageal con- 
nectives, (Plate XII, Fig. 4-a) are exceptionally long in Epi- 
diaspis and, together with this lesser nerve center just mentioned, 
represent the chief differences of the Diaspinz from the other 
forms studied. This pushing forward of the brain and the 
lengthening of the oesophageal commissures is undoubtedly 
a result of specialization arising from the development of the 
mouth-parts. The extremely well developed muscles that 
govern the sucking apparatus are found just below the brain, 
and it is undoubtedly their growth that has pushed forward 
