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The richness of the land fauna of Cleveland is due to the 

 variety of natural habitats the district affords. Coast sand- 

 dunes, salt marshes, rocky cliffs, wide moors of different 

 types, woods, lanes, fields, hills and valleys, all have different 

 resident faunas adapted to the varied conditions of life in 

 each. We may term these faunal groups, "associations," 

 analagous to the plant associations of the botanist, and it 

 will be of no little interest to contrast the faunal associations 

 of the local sand-dunes, pine woods, and moors with one 

 another. 



In the case of the Coatham sand-dunes, the first point 

 which strikes the observer is the gi'eat abundance of Mollusca, 

 nearly a dozen species of land snails being more or less 

 numerous. In this respect the dunes are in marked contrast 

 to the moors which posses no molluscan fauna except the 

 Black Slug (Anon ater). For this contrast there must be 

 some cause, either in the nature of the vegetation, or the 

 differences of climate and soil. No doubt the moors are un- 

 favourable to molluscan life, but it remains to be shown 

 how the various botanic, climatic, and edaphic conditions 

 act injuriously upon these organisms. In the pine woods, 

 slugs are fairly numerous but other Molluscs do not seem to 

 be at all common. 



Numerous species of insects are peculiar to each habitat, 

 and this arises from the fact that they are confined to the 

 special plants growing in these localities. On the sand hills 

 several special Lepidoptera are to be met with, Tapinosiola 

 elymi, and Agroiis valligera among others, as well as peculiar 

 Coleoptera. In pine woods the restricted insect fauna is 

 much more numerous, and to confine our attention to those 

 living on the Scots Pine there are nearly a dozen species of 

 Lepidoptera (such as Trachea piniperda, Ellopia prosapiaria, 

 etc.) ; numerous Beetles (such as the Pine Weevil, Hylobius 

 abietis) ; and Sawflies (such as Sirex juvencus and gigas, 

 Lophyras pint) together with their parasites. Rhyssa 

 persuasoi'ia is the most extraordinary of these parasites on 

 account of its laying its eggs in the burrows of the Giant 

 Saw fly, (S. gigas), on the larvae of which it feeds. These 

 insects form a most heterogeneous association, all united by 

 the fact of their being ultimately dependent upon the pine 

 tree for their existence. 



