A HISTORY OF HERTFORDSHIRE 



Tring, and which is situated almost wholly upon the Cretaceous beds, and 

 this formation being characteristic of a large portion of Hertfordshire, the 

 species enumerated may, as far as they go, be considered as representative 

 to a certain extent of the county generally. In many localities the chalk 

 is overlaid by deposits belonging to the Eocene and Quaternary periods, 

 and there is a corresponding alteration in the character of the flora. Not 

 much is known of the Coleoptera of these districts, but they may reason- 

 ably be expected to produce some species not to be found upon the 

 outcrop of the Cretaceous beds. Where outliers of the Woolwich and 

 Reading beds occupy extensive areas they effect a material change in the 

 character of the soil, and an increased number of species of Coleoptera 

 may be looked for, especially if the outlier be covered with woodland. 

 Upon the chalk we have occurring a considerable number of the species 

 peculiar to that formation, and it will be found that a very close analogy 

 exists between the fauna of the Chiltern Hills district and that of similar 

 districts in the counties of Kent and Surrey. The Middle Chalk which 

 seems so specially favourable to the growth of several of our rare plants * 

 is also apparently the special haunt of many of the rarer chalk-loving 

 beetles. Here there always seems to be a greater variety of species, and 

 two members of the genus Apion, A, atomarium and A. iva/toni, I have not 

 yet noticed on any of the other divisions of the formation. Possibly 

 other observers may find these two species less particular in this respect. 

 The beech woods which flourish in and are such a notable feature of the 

 chalky districts, harbour many characteristic species, principally sub- 

 cortical ones, the beech being very little in favour with the Cryptocephali, 

 Rhynchites and other phytophagous genera usually to be looked for in 

 such situations. The flora of the chalk downs and uncultivated chalky 

 pastures includes a large number of plants which are frequented by 

 various beetles. It is unnecessary to detail them here, as the name of the 

 food plant upon which a species has been found to occur in the county 

 is given in each case in the catalogue with the locality. Even the 

 cultivated fields in the chalky districts are often well adapted to produce 

 an abundance of beetle life, growing as they do crops of sainfoin, lucerne 

 and clover or cereal crops much overrun by charlock (Brassica sinapis), 

 either kind of vegetation being capable of supporting many species of the 

 weevil tribe and Halticidce, and for which there is usually abundant 

 undisturbed shelter during winter in the close-growing turf and moss of 

 the adjacent chalk downs and hedgerows. 



The aquatic Coleoptera are but poorly represented at present in the 

 county list. This is partially due no doubt to the fact that I have not 

 myself collected them quite so carefully as some of the other groups, but 

 it must also be borne in mind that there are no extensive fen or bog 

 lands within the county, so that probably further and more complete 

 search will not very largely augment the number. 



Upwards of fifty of the species appearing in the catalogue are not at 

 present known to occur further north. Many of these are chalk-fre- 



1 Flora of Hertfordshire, pref. p. xiii. 

 84 



