122 MIOCENE LOCALITIES. 



quantity of reeds, reed-maces, and poudweeds that are met 

 with in the "great Mockeii " indicates that the spot was near 

 the shore. The tenches which characterize this rock also de- 

 monstrate a shallow muddy bottom. But the plants gradually 

 disappear, and the " little Mocken/' which may have been in 

 the middle of the mouth of the river, contains no plants. 



A period of perfectly still water succeeded, in which a great 

 quantity of larvae of dragonflies swam about among Oharas and 

 Ulveae (Enteromorpha stagnalis). These larvae are found by 

 hundreds in the dragonfly-bed ; but few of them are well pre- 

 served. Other insects are very scarce; and of land-plants only 

 a few small leaves of an elm, a Weinmannia, and an Edwardsia 

 have been found. Large leaves are entirely wanting, as are also 

 the shore- plants, such as reeds and reed-maces; the locality 

 seems to have become a quiet bay, the shore of which was 

 almost destitute of plants, and small leaves of a few plants 

 which grew upon the shore were carried into the little bay by 

 the wind. 



From the fact already mentioned (vol. ii. p. 24) that dragonfly- 

 larvae of all ages lie intermixed in certain slabs, it would appear 

 that these insects had been suddenly killed, and that they were 

 subsequently enveloped by snow-white limestone. Had there 

 been no violent action, it would be difficult to explain how such 

 quantities of these larvae could have been buried in the rock, 

 some in a running, others in a resting position, with the mask 

 extended or retracted. Dragonflies may have lived on the spot 

 during the formation of both the higher beds and the " Kettle- 

 stone"; but they were not disturbed in their development; when 

 completely developed they rose into the air, and no traces re- 

 main of their larvae. In the next higher bed, dragonflies entirely 

 disappear ; the pondweed again makes its appearance, and with 

 it numerous white fish (Leuciscus). One bed higher, and both 

 plants and fish entirely vanish; but in this bituminous rock, 

 which is known as " Mollen " -stone, fine teeth of a mastodon 

 (M. tapiroides) have been found. Sandy calcareous marls which 

 follow the " Mollen "-stone show a destitution of plants. Both 

 the Mollen-stone and the calcareous marl exhibit a great varia- 

 tion in thickness (from ^ foot to 5 feet) within a very small space, 



