647 riSSICORN TACHINIDAE, WITH DESCRIPTION OF NEW FORMS FROM AUSTRALIA AND SOUTH AMERICA. By Prof. Mario Bezzi, Turin, Italy." (Communicated hy E. W. Ferguson, M.B., Ch.M.) (Eight Text-figures.) [Read 28th November, 1923.] General Bemarks. Smell being the dominant special sense among insects, and its sensory organs being chiefly located in the antennae, these appendages are subject to the greatest modifications. There is, in all the orders except the lower more sedentary forms, the tendency to enlarge the antennal surface, either by increasing the number of the joints or by dilating them, or by adding sensitive hairs, or by the means of ramification or splitting of some parts. These specialisations are usually much more developed in the male than in the female, no doubt because they have some part to play in bringing together the sexes. In the Diptera this tendency has evolved differently among the three main groups in which the order can be divided. In the Orthorrhapha Nematocera the so-called flssicom form is never to be observed, apparently in consequence of the fact that they possess numerous an-tennal joints (6-40, but usually 6-16), approximately similar to one another and arranged in a linear manner. But in certain families there are often projections on the single joints, to form so-called pectinate or bi-peetinate antennae. With-out taking into consideration the elaborate structures of certain Cecidomyidae (of Diplosariae section), and of some Psychodidae (like Brunettia Annandale), or Culicidae (like Lophoceratomyia Theobald), the pectination reaches its climax among the Tipulidae. It is sufficient to recall the genera Rhipidia Meigen, Gynoplistia Westwood, Cerozodia Westwood, Ctedonia Phtlippi, Dirhipis Ender-leiu, Scepasma Enderlein, Ptilogyna Westwood, Phacelocera Enderlein, Ozodicera Macquart, Dihexaclavus Enderlein, Ctenopihora Meigen, Malpliighia Enderlein, Xiphura Brulle, Dictenidia BruUe, and PselliopJiora Osten-Saeken. In other families there is no pectination, but its place is taken always in the male sex by the great development of bushy sensitive hairs, as in the Chironomidae and in the Culicidae; while in the more pedestrian and often gregarious Nematocera anomala there is neither pectination nor plumosity. In the Orthorrhapha Brachycera there are several examples of a pectinate or bipectinate form like that of Tipulidae, as in the Stratiomyid genera Ptilocera Wiedemann and Isomeracera Enderlein; or in the Xylophagid genera BhacMcerus
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