2 EXPLANATION OF TERMS. 



Dimerous. Two-jointed. 



Dorsum. The upper side of the body when the insect is in its natural position. 

 Dorsal. On the upper side or dorsum. 



Eyes. Two coloured, granular or simple, round organs on the cephalic region of 



the female, near the base of the antennae (Plate xiv., Fig. 2, k. ; Plate 



xx., 6) ; two, or four, coloured, granular, simple or facetted, on the head of 



the male (Plate i., Figs. 14, 15 ; Plate xxi., Fig. 2, b). 



Femur. The second joint of the feet, next the coxa, joined to it by the false 



joint " trochanter." (Plate i.,' Figs. 6 /, 7 /.) 



Fringe. A portion of the excreted substance, cotton or wax, produced by the 

 spinnerets on the edge of the body in certain Lccanidina and Heini- 

 coccidina. It may be in the form of long glassy threads (Planchonia) or of 

 more or less broad flat plates (Ctenochiton). (Plate vii., Figs. 2 d, 3 a ; 

 Plate xii., Fig. 2, a, b, c.) 



Haltere. A minute organ, situated just behind the wings of the males, and of 

 which the use, either in this family or in the Diptera, has not been satis- 

 factorily ascertained. It is often termed the " balancer." In the house-fly 

 it has been thought to represent an organ of hearing. In Coccids it is 

 furnished with one or more hooked bristles, and Mr. Comstock affirms that 

 these are, probably for some purposes of flight, hooked into the posterior 

 edges of the wings.* (Plate i., Fig. 17 ; Plate xxi., Fig. 1, m.) 

 Honey dew. A substance of a glutinous character produced by many species, and 



falling in spray from them on the leaves. (See Chap. III.) 

 Larva. The first stage in the insect's life after emerging from the egg. 

 Lobes, in the DiaspidincB, are minute, flat, more or less rounded projections, two 

 or more, seen on the edge of the abdominal extremity, usually interspersed 

 with spines and hairs (Plate iii., Figs. 1, 3, 4, 5, Z) ; in the Lccanidincs, are 

 two triangular or conical projections, usually bearing hairs, on the dorsal 

 side of the body, one on each side of the abdominal cleft (Plate xi., Fig. 3, 

 6,0). 



Mcntum. A kind of secondary rostrum, or "under-lip," not altogether tubular, 

 but rather a deepish trough, through which the rostral setse pass after leav- 

 ing the rostrum. It may have one, two, or three joints. It is not noticeable 

 in the Diaspidinee. (Plate i., Fig. 5, 6.) 

 Metamorphosis, A change of form. For the number and characters of these see 



Chap. II. 



Moniliform. Like a string of beads. 

 Monomer -ous. With a single joint. 



Multilocular. With several divisions : a term applied to the spinneret orifices 

 of some insects, distinguishing them from " simple " orifices, which show 

 only a single tube. Multilocular orifices exhibit a bundle of tubes enclosed 

 together. (Plate i., Fig. 4, c, d, p ; Plate xviii., Fig. 2, e.) 



Nervure. A strong vein which, starting from the attachment of the wing of 

 the male, runs along the anterior edge of the wing, -a little within it : at 

 about half its length a branch runs obliquely towards the posterior edge. 

 (Plate i., 16; Plate xix.,/; Plate xxi.) 

 Normal. According to rule not exceptional. 



Ocelli. Two, four, or six minute circular simple organs, on the head of the 

 male : probably organs of vision. In the Monophlebidcc- they would seem 



*Eeport of the Entomologist, U.S. Dep. of Agric. 1880, p. 277, note. 



