84 
Transactions of the Royal Society of South Africa. 
Considered alone, the measurement of the legs would not form a satis- 
factory character for specific determination ; but, taken in conjunction with 
the antennal segments and the comparative lengths of the setae of the 
anal lobes and of the anal ring, it is an important factor. 
The remarks on the unsatisfactory nature of the first antennal segment, 
for measurement, also apply to the coxa, but, even allowing variation in 
this character, the leg-series of measurements is most useful. The greatest 
importance is attached to the comparative lengths of the femur plus tro- 
chanter and of the tibia, as (always allowing some margin for variation) 
these are remarkably constant for the species. 
An unusual type of trochanter is recorded in the case of Ps. natalensis 
sp. n. Abnormal legs are not uncommon, and occur in the Monophlebinae 
as well as the Pseudococcinae (Fig. 12d). 
(h) Mentum. — The mentum in the 2 series of the Pseudococcinae is, 
I believe, always trimerous, consisting of a bi-lobed basal portion, which, 
is but delicately chitinized, and forms the pivot on which the mentum 
proper turns. The two apical segments are heavily chitinized, and form 
a + pointed cone, the apex bearing a definite series of hairs. The two 
segments may be distinctly separate, or, as is often the case, more or less 
fused into one piece. The approximate size and shape of the mentum vary 
but little among specimens of the same species, but there is often only 
slight variation between different species of the same series. The only 
useful record to be made of this character seems to me to consist of 
the approximate length of the two apical segments, and whether it is- 
broadly or acutely pointed as in Fig. 13a. 
(i) Length of Bostral Loop. — Some writers give this as a specific 
character, but it appears quite useless. Two mounted specimens of 
P. citri, collected at the same time, show the following variation in this 
character : Length of body {a) 3-4 mm ; (h) 2-6 mm. Eostral loop (a) 190 /i ; 
{h) 370 }x. 
(j) Dermal Characters . — Very little attention seems to have been paid 
to the dermal glands and other dermal characters of the mealy-bugs, 
except to note the absence of figure-8 gland-pores in all stages. Occa- 
sional mention is made of a sternal plate," as in the description of 
Phenacoccus iceryoides Green, and of " circular spinnerets," as in Ps. 
ceriferus Newst. ( = Ps. virgatus Ckll.). 
The absence of detailed description results, largely, no doubt, from the 
fact that unstained material was used, for in such slides the dermal 
characters are almost invisible. 
The subcutaneous " tubes " which are iso common in many species of 
mealy-bugs, are only seen in stained specimens. It may not be necessary 
to describe all the dermal characters in detail, but when sufficient species 
have been examined I think certain types can be evolved which will be of 
