ZOOLOGICAL EXERCISES, 
one on each side. On the dorsal surface of the 
abdomen there are nine segments; on the ventral 
surface there are also nine in the male, but only 
seven in the female, the sternum of the seventh 
seoment being much enlarged and produced, serving 
as an ovipositor, and covering the sterna of the 
eighth and ninth seements. At the end of the last 
‘segment there is a pair of flat plates. At the line 
ioining the dorsal plates (terga) of the segments with 
the ventral plates (sterna), there is a row of spiracles, 
one to each of the first seven segments near its 
anterior end. 
2. Specific characters.—Seven species of Bacillus have 
been described from New Zealand. Make out the 
species by means of the following analysis :— 
Abdomen spinous above. 
Head with two tubercles between the eyes—JB. hystriculea. 
Head with ten or twelve black spines—B. geisovit. 
Abdomen not spinous above. 
Abdomen spinous below. 
Basal joint of tarsi crested—JL. horridus. 
Basal joint of tarsi not crested—JB. spiniger. 
Abdomen tubercled below. 
Meso and metathorax spined. 
Head with spines—JS. prasinus. 
Head without spines—JS. gerhardit, 
Meso and metathorax smooth. 
Two black lines on the sides of the head—B. hooker. 
The males are smaller, smoother, and much more 
slender than the females. The females are commoner 
than the males, and are better for commencing the 
study of their anatomy ; consequently, in the follow- 
ing directions, a female is supposed to be the subject 
of examination. 
3, Internal structure—Fasten the animal, temporarily, 
