OiiBERl2. DIPTEHA. G25 



The male organs in some arc accompanied by plate-liKe appendages, 



Ortliocliilc, Latr., lias tlie proboscis lorniing; a small beak. 



In tlie rest tlie proboscis is short, or scarcely prominent. 



Dolichopiis proper, has the third joint of the antcntuT nearly triansulnr, but little elongated, with a seta of 

 moderate length, without a thickened knot between the middle and extremity. 



These insects are often of green or copper colours; the legs are long, and very delicate. They station them- 

 selves on walls, the trunks of trees, leaves, &c. Some run with celerity on the surface of water. The male orgaa.'S 

 of generation are always external, large, complicated, and folded beneath the abdomen. D. loiguhitus, I'ali., the 

 larva of which lives in the earth : it is long, cylindric, with two points in form of two recurved hooks. The piijia 

 has two curved horns in front of tlie thorax, 



Si/bistroma, Meig., has the last joint of the antenna; nearly in the form of the blade of a knife, with a very long 

 seta, knotted beyond the middle. 



The male organs in the others are furnished with filiform appendages. In some the hind part of the antenna; is 

 cither oval, triangular, or very long. 



Rhapkium, Meig., has it very long, and nearly lanceolate. 



Porphijrops, Meig., has it hatchet-shaped or triangular, with a villose seta, the first joint of which is indistinct. 



Medeterus, Fisch., has the seta simple and dorsal, with the basal joint distinct and elongated, and the last joint 

 of the antenna; oval. 



Hydrophoriis, Macq., differs from Medeterus in having the seta entirely terminal. 



In the others, the third joint of the antennae is nearly globose, and the seta always villose. 



Chnjsotus, has it terminal. 



Psilopus, has it inserted rather above. 



Diaphurus, has it inserted lower, and the head nearly spherical, and entirely occupied by the eyes, in the males, 

 thus appearing to conduct us to the next family, Plati/peziricc. The wings, ocelli, and other characters derived 

 from tlie parts of the head, corroborate those which we have mentioned, but it is impossible for us to enter into 

 such details. 



Tbe Platypczlnse of Meigen, from vhich Jlacqiiart has judiciously removed the genus Ci/rfoma, aiul 

 to which we have added that of Scenojjinus, and his family Megacephali, is composed of Diptera very 

 similar in the proboscis, antennae, and wings to Dolichopu.s, bnt the body is depressed, with the head 

 hemisplierical, and almost entirely occupied by the eyes, at least in tlie males. The legs are short, 

 without spines, and with the posterior tarsi often flat and broad. 



These Diptera are very small. Some of them have a seta in the last joint of the antennae. Tho33 

 in which it is terminal, and the eyes contiguous above in the males, form two subgenera. 



Calloim/ia, Meig., has the basal joint alone of the posterior tarsi dilated, but as long as all the rest united. 



Plaljipeza, Mi'ig., has the four basal joints of the posterior tarsi tlattened. 



PipuncuUis, Latr., (Ccphalopx, Fall.), has the seta inserted on the back of the third joint, near its base; the 

 tarsi are not dilated, the eyes not united above in either sex, and the head noariy globose. 



Scenopinus, Latr., has no seta to the terminal joint of the antenna, which is narrower and longer than in Ihc 

 preceding. 



THE TIIIRD FAMILY OF THE DIPTERA,— 



1 



I 



The Tabanides, — 



Has, for its characters, a proboscis exserted, and generally terminated by two lips ; with the palpi 



porrected, the last joint of the antennx annulated, and a sucker of three pieces. It comprises the 



genus 



Tabanus, Linn., — 



And is composed of large flies, well known for the torments they inflict upon horses and cows, of 

 which they pierce the skin, in order to suck their blood. The body is generally but slightly hairy; 

 the head is as wide as the thorax, nearly hemispherical, and covered, except in a narrow space, particu- 

 larly in the males, by the eyes, which are generally golden-green, with purple stripes. The antennae 

 are nearly as long as the head, 3-jointed ; the last joint being terminated in a point without seta or 

 style at the tip, often notched at the base above, with transverse divisions, in number from three to 

 seven. The proboscis in the greater number is nearly membranous, perpendicular, of the length of 

 the head or rather shorter, nearly cylindrical, and terminated by two elongated lips ; the two jialpi 

 mostly rest upon it, and are thick, villose, conical, compressed, and 2-jnintcd ; the sucker, inclosed in 

 the proboscis, is composed of six pieces like lancets, and which from their number and respective situ- 

 alion represent the parts of the mouth of the Coleoptera. [It is only the females which possess this 

 tiuuilifr "f lancet?; tlie nriiitii of the males is mucli weaker, and has only four. This s?x is harmless, 



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