CRUSTACEANS 



As a representative of British carcinology Devonshire may claim to be the premier county. If 

 It be conceded that Thomas Pennant outside its boundaries already in the eighteenth century had 

 something of the modern spirit in his treatment of crustaceans, he was still devoid of initiative, and 

 never rose to the level of contemporary continental progress. It was reserved for Devonshire in the 

 opening years of the nineteenth century to give scientific dignity to this branch of the English fauna. 

 An example was set of adequately describing new species. Improvements in classification were 

 originated. A zeal for collecting specimens and observing their habits was inspired, and interest in 

 the whole subject was astonishingly quickened and sustained. 



For this class of animals Devon shares with Cornwall a favourable situation in the south-western 

 peninsula of Great Britain. With the Bristol Channel forming its northern and the English Channel 

 its southern border, it might have been expected to derive some advantage from a double coast-line, 

 but the diversity of aspect has not at present yielded any marked divergence between the northern 

 and southern groups of species. Comparative paucity in the north may naturally be explained by 

 lessened salinity in that channel which is continually receiving a vast admixture of fresh water from 

 the Severn. The maritime parts of Devon, like those of Cornwall, are diversified by sheltered bays, 

 by harbours of varying importance, and tidal estuaries. They are much frequented by shipping, 

 which plays its own unconscious part in the distribution of Crustacea. They give occupation to 

 fleets of trawlers and other agencies of the fishing trade, by which again the branch of zoological 

 scierice with which we are here concerned is materially assisted. The scalloped and indented out- 

 line of the coast, as seen on a map, prepares the naturalist for what he actually finds. There are 

 not only wave-beaten headlands and pebble beaches, which brittle-coated animals not unnaturally 

 mislike, but at intervals there are low rocky ledges coated with seaweed and pitted with clear but 

 weed-fringed pools wherein many quaint sea creatures love to dwell, and at other intervals come long 

 stretches of sand, barren to the untutored eye, though teeming with life for those who know how to 

 search it out. 



Owing, perhaps, to the attractive richness of its marine fauna, the inland waters of the county 

 have been comparatively neglected. These, however, are not likely to be less prolific in freshwater 

 Entomostraca than those of our counties in general. In that, as in other respects, the diligence 

 of research may in time bring about a far greater equality in our faunistic catalogue than at 

 present exists, at least wherever the conditions are reasonably comparable. It is a question which 

 cannot at present be answered with assurance, whether the crustacean population of marshes, 

 ponds, ditches, rivulets, rivers, and lakes, differs essentially in various parts of the country. 

 Under exceptional conditions, such as those presented by brine-pools, large lakes, and high- 

 perched mountain tarns, species may be found with a very limited distribution ; but this limitation 

 will most likely be traceable to the needful environment, not to the latitude or longitude of any 

 particular county. 



Marine crustaceans have their own great and obvious facilities for dispersion. There can be 

 but few, if any, of the species which would be daunted by the journey round the coast of England. 

 Many of them are well equipped with apparatus for walking or swimming. Much of the travelling 

 can be performed by hugging the shore or launching out into the deep. They have at command 

 assisted passages on vessels steering a course or wreckage in a current, on slowly-floating weed or 

 swiftly-swimming fishes. The course of a species from point to point need not be accomplished 

 within the lifetime of an individual. It is open to patient, gradual achievement by an indefinite 

 succession of generations. Still, from this view of the matter one cannot infer anything like 

 complete uniformity of distribution. It is possible that a close observer, by spending years over the 

 quest, might in the least favoured of our sea-board counties come across examples of almost all the 

 English marine crustaceans, whereas probably the same investigator would in Devon attain the same 

 result with a tenth part of the time and labour which he had had to bestow elsewhere. It will easily 



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