ORTALIDSE — INTRODUCTION. 7 



shape of the ovipositor : its first joint is smaller, narrower, and 

 somewhat less flattened ; generally also more withdrawn in the 

 last abdominal segment. The hypopygium, formed by the upper 

 half of the fifth abdominal segment, is unusually small ; whether 

 the penis has the shape of an unrolled tape or thread I cannot 

 ascertain at present, as I have no fresh specimens at hand, but I 

 have every reason to suppose that such is the case, as the female 

 ovipositor, in its structure, is absolutely analogous to that of the 

 species of Ortalis. The agreement of all other characters com- 

 pels us to admit Platystoma among the Ortalidse; and this genus 

 really shows, in the four-jointed abdomen of the female, the ab- 

 sence of bristles on the pleurae and an analogous structure of 

 the mouth, a close relationship to Ortalis syngenesise. 



I know of no other European genera which, in following the 

 same direction of relationship, might be still more distant from 

 Ortalis than the species of Platystoma are, and which, neverthe- 

 less, would show a sufficient agreement with the Ortalidse to 

 be placed among them. I, therefore, hold Platystoma to be one 

 the more distant genera, placed on the extreme limit of the 

 family. 



3. Forms reminding of Ortalis paludum. 



Species like Ortalis paludum, luctuosa, and others of the 

 same group, remind of the genera Psairoptera and Cephalia. 



The comparatively low head, the transversely oval eyes, and 

 the small development of the clypeus give Psairoptera a very 

 peculiar appearance ; nevertheless in all the other important 

 characters it agrees with the species of Ortalis so well, that its 

 position among the Ortalidse cannot be disputed, although its 

 precise location within this family may not be very easy to de- 

 termine. The ralationship of Psairoptera with the above-named 

 species of Ortalis, far from being a close one, can rather be called 

 distant, 



In Cep>halia I cannot discover a single character which would 

 justify its separation from the Ortalidse. To place this genus 

 among the Sepsidse seems to me utterly impracticable, as the 

 distinctive character of the latter family, the rudimentary struc- 

 ture of the palpi, must be maintained, unless we render the limits 

 of the family altogether doubtful. Moreover, Cephalia does not 

 show any vestige of vibrissa which the Sepsidse possess, and 

 more than all, the structure of the ovipositor of Cephalia is like 



