by r. j. tillyakd. 281 



Discussion of the Relationship of the Genus Mesogeeeon with the 

 Jurassic Palaeontinidae. 



In my work on the Panorpoid Complex, I followed Handlirsch in coui^ider- 

 ing the Jurassic family Palaeontinidae as belonging to the Order Lepidoptera 

 (1908, pp. 654-8). 1 pointed out, however, certain characters which prevented us 

 from assigning them to either of the two Sub-orders of the Lepidoptera existing 

 to-day, and suggested that they should be considered as a separate Sub-order 

 Palaeontinoidea. 



It is, of course, well known that both Oppenheim «(1888) and Haase (1890) 

 considered certain of the Palaeontinidae which they described to be Homoptera 

 related to the Cicadidae; viz., the genera Prolystra, Beloplesis and Eocicada. 

 Others were placed in the Lepidoptera, viz. Phragmatoecites and Palaeocossus. 

 Butler placed the well known forewing of Palaeontina ooUtica in the Lepidoptera. 

 Thus there was, from the first, considerable doubt about the correct position of • 

 these fossils. Handlirsch, after studying many of the type-specimens and de- 

 scribing other new species, summed up his conclusions as follows (1908, p. 619, 

 translated from the original German) : — 



(1) In several of these fossils the covering of scales on the wings is quite 

 plainly visible. 



(2) The Limacodidae just mentioned do not visit flowers, and are, no doubt, 

 old forms whose mouth-parts remain at an archaic stage of development, s imi lar 

 to the Hepialidae, etc. (N.B. Handlirsch claims a close affinity between the 

 Palaeontinidae and the existing Limaeodidae.) . 



(3) The resemblance of these fossils to the Cicadas is only a very superficial 

 one, and their venation can in no way be traced back to that of the Homoptera. 



(4) The venation of the fossils is strikingly similar to the course of the 

 tracheae in many pupae of recent Lepidoptera. 



At the time when I discussed this family in the Panorpoid Complex, I had 

 not, of course, seen any of the actual fossils, and had been content to accept 

 Hundlirsch's statement, tliat the covering of scales could be quite plainly 

 seen in some of them. However, during my recent voyage round the world, 1 

 studied all those Palaeo>Uinidae to which I could get access, and was surprised 

 to find myself quite unable to agree with Handlirsch's conclusions. The results 

 which I obtained may be briefly stated as follows : — 



(1) The original type of Palaeontina oolitica Butler was studied by me in the 

 Geological Museum, Jermyn Street, London. This is a very badly preserved im- 

 pression of a forewing, from which it would be quite unsafe to draw any definite 

 conclusions. It is clear, however, that M has four quite distinct branches, which 

 occupy most of the distal portion of the wing, so that the branches of R, which 

 are indistinct, are pushed up towards the costal margin. There is no sign of 

 tlie formation of a Y-vein between M4 and Cuia. Thus, in so far as this speci- 

 men offers any evidence at all, it is not in favour of any Lepidopterous aflinity. 

 (No sign of scales can be seen, but this could not be expected in so poorly pre- 

 served material.). 



(2) Professor Lameere, of Brussels, kindly handed to me for study the 

 original type of Eocicada lameerei Handl. Witli respect to this insect, Hand- 

 lirsch has stated definitely that he could see the scales on the wings (1908, p. 

 627, "Am mehrerer Stellen haben die Schuppen ganz deutliche Eindrucke auf 

 der Platte hinterlassen"). The specimen is only moderately well preserved, like 

 most of the insects from the Solenhofen Beds. Handlirsch's photographic repro- 



