56 MIOCENE FAUNA. 



remarkably large fly. It is destitute of feet, and has a very 

 small head, three distinct thoracic, and nine abdominal segments, 

 on the dorsal surface of which are fine undulating striae. 



G. Lepidoptera. 



The Lepidoptera are seldom met with at CEningen ; and as all 

 the other localities for fossil insects have furnished very few 

 species, the Lepidopterous order of insects must have been very 

 scarce in the primaeval world. It is probably the youngest order 

 of insects j but in the present fauna it has been so largely de- 

 veloped that it has become one of the richest in species. From 

 CEningen there are traces of only three species, belonging to the 

 Nocturna. Of one species (Psyche pineella, Heer) the larva-sac 

 has been found, which was made of the leaves of pines ; of a 

 second (Bombycites ccningensis, Heer) only fragments of the 

 wings and body have remained to the present time ; and of the 

 third (Bombycites Buchii, Heer, fig. 310) there is a pretty well- 

 preserved caterpillar*. 



3. VEETEBRATA. 

 a. Fishes. 



Important information may be derived from the distribution 

 of fossil fishes with reference to the communications of ancient 

 basins of water, as the investigation of the fish-fauna of the dif- 

 ferent river-regions of the present day shows that each course 

 of water possesses a number of peculiar species. Thus the 

 salmon and the eel are found in all rivers which are connected 

 with the North Sea, the Baltic, the Atlantic, and the Mediter- 

 ranean, whilst they do not occur in the rivers and lakes which 

 flow into the Black Sea. The salmon- trout, the shad, the 



* As yet, only one specimen has been found. It is preserved in the col- 

 lection at Zurich, and the counterpart in that at Winterthur. It is much 

 crushed, and the boundaries of the segments are difficult to distinguish. The 

 head is small ; the thorax enlarges rapidly ; the thoracic feet are not pre- 

 served ; the abdominal feet are in part indicated as black tubercles. Of the 

 stigmata four may be recognized. Similar caterpillars occur among the 

 Bombycidse and Pseudo-Bombyces (Arctiidse). 



