186 The Phytoptus of the Vine. By Prof. Giovanni Briosi. 
triangular fissure ; the smaller and hindmost side is represented by 
the under and triangular lip (Fig. 12, 2) of the mouth. © This 
opening is not always open, as the animal can bring the lateral 
sides so near as almost to touch one another, and also the sides of 
the angle projecting from the lower lip (Fig. 3), thus forming a 
tube which it uses for sucking, This cavity seems to enclose two 
very small mandibles &, 7, lamellary, and terminating in a pointed 
manner, which sometimes are placed on one another in such a 
manner as almost to resemble a single point (Fig. 5). The animal 
can draw in or lengthen these mandibles at pleasure (indeed they 
are seen in various lengths, and sometimes not even the smallest 
point of them projects or can be distinguished), and they can reach 
up to the front end of the opening, and perhaps even beyond. 
With these the mite must prick the leaves in order to suck the 
juice afterwards with the cephalic or buccal extremity which is 
transformed into a tube. The length of the thoracic region, from 
the point where the rings end to the extremity of the head, 
measured on the average 0°0265 mm., in animals whose whole 
length was 0°09 mm., viz. about one quarter of the total length 
of the body. ‘The development, however, of the curved upper or 
dorsal line of the cephalo-thorax of the same animals, from the 
spot where the dorsal bristles are inserted up to the top of the 
head, was on the average 0°0306 mm. 
‘The skin of the abdomen, as said before, is externally covered 
with ring-like elevations, which are found flat and nearly level with 
the axis of the body, and cease all of a sudden at a short distance 
from the anal opening, leaving a small part of the belly (about 
0-0085 mm.) perfectly smooth. I never counted more than seventy 
rings, generally only from sixty to sixty-six; their size in already 
developed animals varies from 0°00111 mm. to 0°0017 mm. 
Sorauer in the Phytoptus piri found, however, from fifty to 
eighty rings; and Landois in the Phytoptus vitis counted from 
120 to 180, each measuring 0°0013mm. But as, according to 
Landois, the average size of the longest (female) animals is 
0°13 mm., with a diameter of 0°035mm., the numbers of the 
rings must necessarily be a mistake, as otherwise the length of 
that part of the body which is covered with rings would exceed that 
of the whole body. Under great enlargement I observed that these 
rings are not smooth or uniform, but that each of them result from 
a series of raised corpuscles, just as Sorauer saw them in the 
Phytoptus piri. 
The anal opening is placed at the lower end, in the middle of a 
kind of disk which is a little hollowed out, in which the body 
terminates. 
On the body I found six pairs of bristles, two on the dorsal 
surface (one on the first, the other on the last ring), and four on 
