FAUNAL ASSOCIATION. 21 



Insecta — (continued). Insecta — (continued). 

 Protorthoptera. Blattoidea — (continued). 



Xeroptera obtusata, Bolton. Aphthoroblattina eggintoni (Bolton). 



Scalteoptera recta, Bolton. Archimylacris iitcita (Bolton). 



Coselia palmiformis, Bolton. Plnjllobtatta transversalis (Bolton). 



Blattoidea. Larval Blattoid. 



Aphthoroblattina johnsoni (Woodw.). Leptoblattina exilis, Woodw. 



Coalbrookdale Coalfield, Shropshire. — Ironstone Nodules of the Pennystone 

 Series. 



EUCRUSTACEA. . ArACHNIDA (cO)lf ill HCtt) . 



Euphoberia ferox, Salter. Curculioides ansticii, Buckland. 



Anthrapalsemon (Apus) dubius (Prestw.). Eophrynus prestvici (Buckland). 



Arachnida. Diplopoda. 



Prestwichia anthrax (Prestw.). Acantherpestes brodiei, Scd. 



,, rotundata (Prestw.) Insecta. 



,, trilobitoides, Woodw. Lithosialis brongniarti (Mantell). 



South Wales Coalfield. — Shales in the neighbourhood of the Mynddislwyn 



Vein, base of the Upper Coal Measures. 



Arachnida. Insecta. 



Aphantomartus areolatus, Pocock. Aphthoroblattina sulcata (Bolton). 



Grseophonus anglicus, Pocock. Orthomylacris lanceolata (Boltou). 



Maiocercus celticus, Pocock. Archimylacris hastata (Bolton). 



Kreischeria verrucosa, Pocock. ., obovata (Bolton). 



The arthropod association in the lists given is significant, for no other animals 

 enumerated are so readily water-borne as are insects. It may be assumed that 

 neither the more primitive arthropods, nor the insects, have been transported to 

 any great distance from their former habitat. Their preservation under similar 

 conditions supports the belief that their habits and habitats were the same, or 

 closely approximated to the same conditions of entombment. 



The freedom of the deposits from comminuted carbonaceous matter, such as is 

 usually a chief constituent of the Coal Shales, may be accounted for by the beds 

 having been laid down in quiet lagoons or swamp lakes, into which only the finer 

 mud particles and floating pinnules and debris of coal-plants could pass and 

 accumulate. Such waters were probably fresh or brackish, shallow, and limited 

 in area. As we have indicated elsewhere (p. 10), it has been considered that the 

 larvas of many of the Coal Measure insects were semi- or wholly aquatic, and if 

 such was the case, they w r ould be more likely to be found in the deposits accumu- 

 lating in quiet waters than in others exposed to movement. The presence of 

 Mollusca and the lower orders of Arthropoda, with such forms as Palaeoxyris, and 

 even fish-remains, can be accounted for by the existence of occasional or 

 permanent passages leading to open waters, such as river channels and the 

 open sea. 



