viii EuRorEAN Butterflies and Moths. 



These branches are called sub-costal ncrvules. The median nervure divides into three branches, 

 which mostly run to the hind margin, and are called median nervules; and one branch runs 

 from the disco-cellular nervules, which is called the discoidal nervule : it is sometimes fainter 

 than the others, or is absent. There are two discoidal nervules on the fore-wings of the 

 Papilionid(T;. It happens exceptionally that one or two branches run from tlie disco-cellular 

 nervules instead of from the sub-costal or median nervures, or the discoidal nervule itself 

 rises from the median nervure. The neuration of the hind-wings is almost identical with 

 that of the fore-wings in the Hcpialidce (Fig. 34, which represents a hind-wing). The rami- 

 fications of the sub-costal nervure are very various, as its branches often sub-divide or touch 

 one another, thus forming net-like patterns. One nervule or another is sometimes wanting on 

 the hind-wings (Fig. 32). 



The separate nervules are indicated by numbers, and are always counted from above down- 

 wards, i.e., in the direction from the costa towards the inner margin, and not vice versa. This is 

 the English and French notation. The German is somewhat different, and is shown in Fig. I (left 

 side). According to this system, the nervures and nervules are counted in the opposite direction, 

 or from below upwards, i.e., from the inner margin towards the costa. This system is very simple. 

 All the nervures and nervules which run to the inner margin are numbered \a, \b, &c. ; and those 

 which run to the hind margin are numbered 2, 3, 4, &c. These are numbered from 2 to 1 1 on 

 the fore-wings, and from 2 to 7 on the hind-wings. The discoidal nervule is always numbered 5 ; 

 and the sub-costal nervure is numbered 12 on the fore-wings, and (generally) 8 on the hind-wings* 

 and they retain these numbers, even when some of the nervules are absent. I have thought it 

 necessary to explain this notation in full, because it is continually employed by German authors ; 

 and unless it is clearly understood from the outset, those who may wish to refer to German 

 entomological works would often find them unintelligible. 



The space enclosed by the sub-costal and median nervures is called the discoidal cell (Fig. i, mz), 

 and the space between this and the hind margin is called the disc. When the disco-cellular nervules 

 are perfectly formed, the discoidal cell is said to be closed; but when they are absent, or imperfectly 

 formed, it is said to be open, or imperfectly closed. The intermediate spaces between the nervures 

 and nervules are called cellules ; and as there is no complete English or French classification of 

 them, I think it well to add th'e German notation for these also, which is very full and satisfactory. 

 When the discoidal cell is divided longitudinally by one or two fine nervures, the divisions are called 

 the front, middle, and hind discoidal cell respectively. When portions of the discoidal cell are 

 divided from it by nervules, or if two nervures run together or are united by a tran.sverse nervule, 

 the spaces thus enclosed are called accessory cellules. The accessory cellules are divided into 

 intrusive cells when they lie before the disco-cellular nervules, and are bounded by these and 

 by dividing lines which unite towards the base (Fig. 31,^,7); and appendicular cellules when they 

 are formed by the junction or crossing of nervules beyond the discoidal cell (Fig. \,az). Each 

 marginal cellule is indicated by the nervure or nervule which lies below it, i.e., on the side of 

 the inner margin. Thus the cellule between \a and \b (or the first and second sub-median nervures) 

 would be called cell \a; that between 11 and 12 (or the costal and the first sub-costal nervules) 

 would be called cell 1 1, and so on. (The cellules are numbered on the left side of Fig. i.) 



When the wings are imperfectly developed, the neuration is also modified, especially by the 

 absence of certain nervures. The neuration is also simpler in the narrow-winged Tineina, in 

 which the discoidal cell is inconspicuous or disappears altogether, and only a few nervures remain, 

 some of which are branched. 



TJic connectins; bristle. — We must now mention another structure which is connected with the 



