110 



C O N C H O L O G Y. 



fresh water, also produce pearls the Pinna marina, 

 Tridaciia gigas, Unia, Mussel, &c. ; they are, however, 

 far inferior in beauty and value, though Suetonius in- 

 forms us that the pearls found in Britain were so highly 

 extolled at Rome, that they mainly influenced Caesar's ' 

 invasion of our sea-girt isle, and though his ambitious j 

 views were only in part realised by the attempt, he ! 

 did not lose sight of one of the inducements which ! 

 led to it, and a buckler, richly decorated with British ' 

 pearls, was placed on his return, in the gorgeous ! 

 temple dedicated to Venus Genetrix, as a trophy of ' 

 his mad ambition, and an imperial offering worthy the 

 sea-born goddess. The rivers and seas of Ireland, 

 Wales, and Scotland still yield pearls ; even to a late 

 date fisheries of them have been established, but the i 

 produce is comparatively of so little value that it no ' 

 longer repays the speculator. A remarkably fine 

 Welsh pearl is said to have been presented by Sir 

 Richard Wynne, of Gwyder, to Catharine, Queen of 

 Charles II., and still to hold its place in the regal 

 crown of England. 



In the alphabetical arrangement of this work, pearls 

 will be more amply described, and an account of 

 the Oriental pearl fisheries given. 



Having enumerated some of the known benefits 

 mankind derive from shells, whether as food, ornament, 

 or otherwise, it will be proper to point out such as 

 are injurious, or so considered in certain points of 

 view, that is, so far as their habits tend to defeat the 

 industry or ingenuity of man ; but here, as in the 

 instance of the common snail, we feel called upon to 

 enter a philosophical protest against treating them 

 indiscriminately as destructives and enemies. The 

 evil they commit is certainly manifest, but it is con- 

 fined to a very limited circle it may be everywhere 

 checked, or prevented by care or art while the good 

 they perform, being unseen and extended over an 

 immense space, passes unheeded, and, in the present 

 stage of our knowledge of natural history, is not 

 appreciated as it should be ; let it, however, be 

 remembered, that there is an eternal fitness of things 

 which requires that the decrease of various portions 

 of creation should, in some degree, keep pace with 

 their otherwise superabundant growth, thus balan- 

 cing the account of nature's dealings, and regulating 

 the expense of life. Extensive mischief is doubtless 

 committed by that insidious little animal the Teredo, 

 which recklessly wends its way in ten thousand tortu- 

 ous paths, through the hardest oak, or toughest teak, 

 rendering them like sponge, and destroying their 

 texture as supports to submarine erections, occasion- 

 ing, in certain localities, dangerous consequences ; 

 piles, jetties, piers, and vessels, long stationed in some 

 climates, are subject to their ravages, from which 

 fatal accidents have resulted. It is not in human 

 nature thus to witness the destruction of the noblest 

 \vorks of our ingenuity, without condemning the 

 agents that have effected it ; but these are no more 

 than additional illustrations of the fact, that it is for 

 man's ultimate benefit such occurrences should take 

 place they give a stimulus to his industry set his 

 wits to work teach him to counteract the evil com- 

 mitted against his immediate interest or convenience, 

 and often create a far greater eventual benefit than 

 he could at first sight discover. The wise man only 

 becomes so by not despising the humblest information, 

 he is constantly examining, inquiring, or reasoning on 

 everything around him ; and some of the greatest 

 efforts of genius have been perfected from the indica- 



tions furnished from apparently trivial causes, over- 

 looked at first from their insignificance. Another of 

 the number of shells but little loved by mariners, is 

 the Balanus or Barnacle, whose numerous broods 

 spread themselves in thick congregations, sometimes 

 as it were incrusting the bottoms of ships, and their 

 sides below the water mark, to such an extent, that 

 her progress through the pathless sea becomes seri- 

 ously impeded : the watchful sailor baffled in his 

 best exertions, and the wealthy speculator disappointed 

 in his nicely calculated hope of gain. To conclude 

 our list of commonly called destructives in conchology, 

 we shall add the Photos, and other of the penetrating 

 genera of shells, whose habitations are formed in 

 calcareous, and even stony matter, wood, &c., there 

 performing either good or evil according to the par- 

 ticular circumstances of their situation and the pur- 

 poses of their being, which are, if well considered, 

 probably more beneficial than prejudicial to mankind. 

 Shells are abundantly distributed over ever}* part 

 of the globe, from the polar regions to the torrid and 

 inter-tropical zones, increasing in number, size and 

 colour, as they recede from the one and approximate 

 the other, a fact equally to be observed in the other 

 works of creation. Heat and light, as we shall here- 

 after explain, possess such a prodigious influence on 

 these productions, that the most beautiful, whether 

 marine or terrestrial, are those inhabiting tropical 

 climates. It may be said, that no part of the world 

 is divested of shells, either terrestrial, marine, or 

 fluviatile, and the number of their species is always 

 proportioned to the extent of their peculiar location 

 or habitat ; we may also ascertain that nearly all the 

 families exist in the different zones of the globe, 

 though the genera and species of some are far more 

 numerous in one zone than in the other. To attempt 

 a detailed account of the geographical localities of 

 the different genera, would not only be extremely 

 difficult, if not totally impracticable, but would occupy 

 a larger space than can conveniently be allotted to 

 the subject in a work like the present one; we will, 

 nevertheless, point out a few leading facts with regard 

 to the habitat of shells, which will serve as a general 

 illustration of the localities of their congeners. In 

 the high northern latitudes shells are not numerous, 

 and the species most usually found are of the genera 

 Terebratula, Mya, Pandora, and some of the Solens ; 

 they are not, however, equally abundant in all the 

 northern seas. The Ostrea, Avicula, Orbicitla, Crania 

 Terebratula, Haliolis, Pecten, Patella, Area, l.'nua 

 Mactra, Pholas, Salanus, Cardium, Teredo, and Helix 

 are everywhere found in greater or smaller numbers 

 as the degree of latitude varies ; the Clavagella 

 Aspergillum, and Fistulana, appear confined to the 

 equatorial zones ; the Vulsella, Perna, Chama, Crc- 

 natula, Trigonia, and some of the Cardia, inhabit the 

 southern zones ; the Harpa, Tcrebra, Cassis, Plcuro- 

 toma, Mactra, Strombus, Conus, Oliva, Ovjila, Cypra'a, 

 &e., principally inhabit the inter-tropical regions ; the 

 Tridacna has not yet been met with anywhere than 

 in the Indian archipelago: the Argonauta, Nautilus, 

 and Spirula, mostly dwell in the torrid zone. With 

 respect to terrestrial species of shells, it may be 

 observed generally, that they are more numerous 

 higher coloured, and of a larger growth, in the 

 southern and eastern regions, than in the northern 

 and inter-tropical. Our Helix ncmoralis, field snail, 

 is, however, a remarkable exception, as its colours vie 

 with those of its congeners in any other country, and 



