Xo. 64] DIPTERA OF CONNECTICUT: MORPHOLOGY 29 



females of higher Diptera the piercing tip of the "ovipositor" is also 

 called a style. If the Latin form ''stylus" is used for the abdominal 

 st^'li, it is possible to use tlie English form of the ^Yord for the an- 

 tennal ""style" without creating undue confusion, but the designation 

 ""ceratostyle" is more specific for tlie antennal structure, and should 

 be used where there is any chance of confusing the terms. The dis- 

 tinction between a style and an arista is not always very clear, since 

 the two types of structures intergrade, but in such cases it is unim- 

 portant which term is applied to the structure — except that a style is 

 always terminal, while an arista may be either terminal or dorsal. 



The arista-bearing type of antenna mentioned above is called 

 aristate (Fig. o.W), while the stylus-bearing type is called stylate 

 (Fig, 5, Gr). When the segments of the antenna bear processes giving 

 it a comb-like appearance, it is called pectinate; and if the processes 

 are double, it is called bipectinate (Fig. 5, H). If the processes are 

 very long, as in Fig. 5, U, the antenna is called flabellate, although 

 this type of antenna is not quite the same as tlie flabellate type in the 

 Coleoptera. When the segments of the antenna bear wliorls of hairs, 

 as in Fig. 3, E, the antenna is called verticillate, and when the whorls 

 of hairs are very dense, giving the antenna a feathery appearance, as 

 in Fig. 5, V, it is called plumose, although this type of antenna is not 

 the same as the plumose antenna of a male moth, for example, and it 

 would be more accurate to refer to it as densely verticillate. The 

 verticillate antenna of the psychodid shown in Fig. 5, C, approaches 

 the nodose type occurring in many cecidomyids, in which the central 

 portion of the segments is swollen to form a knot. If the knots are 

 not widely sej^arated, and give a beaded appearance to the antenna, it 

 is called moniliform. The club-shaped antennae of certain asilids, 

 mydaids, etc., are called clavate; and the slender thread-like antenna 

 of the trichocerid shown in Fig. 5, A, is called filiform.* 



It has been suggested that a 16-segmented, filiform type of an- 

 tenna, like that of Tricliocera (Fig. 5, A), in which the scape, s, and 

 pedicel, ^, are rather short, and the postpedicel. ;?/?, is fairly long, 

 represents the basic type for the Diptera in general,** and this type is 

 very like the antenna of the mecopteron Bittacus. which has retained 

 many of the features of the ancestors of the Diptera. A slight ad- 

 vance is illustrated by the Anisopus ty]:)e shown in Fig. 5. E. in Avhich 

 the segments become somewhat broader: and in some of the higher 

 Nematocera, such as the simuliid shown in Fig. o,D, the antenna be- 

 comes greatly shortened, and the number of segments is reduced. In 

 the tabanids (Fig. 5, 1), the four distal segments become much smaller 

 than the three basal ones, while in the asilids (Fig. 5,G), the distal 

 segments become still more reduced, although the three basal segments 

 are well developed. In the oscinid fly shown in Fig. 5, Q, the post- 

 pedicel, pp, still bears the smaller segments at its tip, but its ventral 

 region becomes prolonged downward to some extent, and this tendency 



♦Many more types of antennae occur in the Diptera, and some of tliese are of con- 

 siderable interest — e. g.. the broad compressed antennae of the mycetophilid Cero- 

 platus (Pig. 5, P) which have "fohaceous", flattened. leaf-Hke segments, etc. 



**It is probable, however, that the ancestors of the Diptera had antennae composed of 

 more numerous segments. 



