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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



common and destructive insect known as the 

 cockchafer may serve as the type. Their early 

 life is spent in darkness, since when larvae they 

 live underground, devouring the roots of plants. 

 When mature their colors must be pronounced 

 far less brilliant than those of their near allies, 

 the rose-beetles (Cetoniadae), which are equally 

 nursed in darkness. It will be, of course, ob- 

 jected that the adult cockchafer is a nocturnal 

 — or, at least, a twilight-loving — insect, while 

 the rose-beetle feeds and flies by day. We will, 

 therefore, take another instance — that of the 

 Elateridae, or click-beetles. As larvae they, like 

 the immature cockchafer, live underground, but 

 when mature they are diurnal in their habits; 

 yet the general coloration of the family is what 

 some people call " sober," scarcely more gay 

 than that of the Melolonthidae, and forming a 

 most striking contrast to that of the Buprestidae, 

 whom they so closely approach at once in their 

 structure and in the degree of light which they 

 encounter, both in their earlier stages and in ma- 

 ture life. Again, we may consider the weevils 

 (Curculionidae), all of them when larvae burrow- 

 ing from daylight in the interior of fruits and in 

 the buds and stems of plants ; yet, when mature, 

 some of them — e. g., the diamond-beetle — are as 

 remarkably brilliant as others are conspicuously 

 sombre. 



On the other hand, attention is drawn to the 

 Chrysomelidae, to which the redoubtable Colorado 

 beetle — vilely called the potato-bug — belongs, a 

 family very richly and brightly colored. Their 

 larvae are active, and they are thus throughout 

 their lives exposed to the sunshine. 



Among the animal population of the seas and 

 livers, also, we meet with facts, not a few, diffi- 

 cult to reconcile with the hypothesis under ex- 

 amination. It must be admitted that in all 

 waters, save the very shallowest, the amount of 

 light enjoyed must be very decidedly less than 

 that which falls upon the surface of the land in 

 similar climates ; yet we do not find that the 

 denizens of the waters are, as a general rule, less 

 vividly colored than those of the dry land. On 

 the contrary, fishes, crustaceans, mollusks, be- 

 sides aquatic forms lower in the scale of exist- 

 ence, such as the sea-anemones, display all the 

 colors of the rainbow in a purity and in a pro- 

 fusion rivaling what we observe in the most gor- 

 geous birds and insects. We admit that splendid 

 oceanic forms are more abundant in tropical 

 waters than in higher latitudes, and also that in 

 a majority of cases the inmates of shallow waters 

 are more vividly colored than the dwellers in 



deeper and consequently darker seas. But what 

 must be inferred from the following observations, 

 extracted from a paper by H. N. Mosely, late 

 naturalist to the Challenger Expedition, read be- 

 fore the Linnacan Society on February 15, 18'7'7 ? 

 "A species of Edwardsia, from 600 fathoms, has 

 undergone but little modification from the littoral 

 form. The Cerianthus, from 2,*750 fathoms, is 

 like its shore-brethren. Thus one species is 

 found in shallow water at the Philippines, under 

 the full glare of the tropical sun, while another 

 species exists at three miles' depth, where solar 

 rays never penetrate, and where the water is at 

 freezing-point. The deep sea-anemones retain 

 vivid colors in the dark." 



This fact is very suggestive. It agrees ill 

 with the often-expressed view of teleologically- 

 disposed naturalists, that all the brilliant hues 

 of animal and vegetable life have been called into 

 existence for man's delectation ; but no less does 

 it clash with the conclusions drawn from the 

 paleness and obscurity of certain nocturnal, sub- 

 terranean, or cave-haunting animals, such as the 

 Coleopterous larvae to which we have referred, 

 wood-lice, crickets, etc. Light, it would seem, 

 is not the sole condition for the production of 

 positive color ; nor arc the dwellers in darkness 

 necessarily restricted to a garb of whites, blacks, 

 and grays. It can, further, scarcely be contended 

 that the land-shells of any country are more 

 vividly and intensely colored than the marine 

 shells of its coasts, many of which are as highly 

 decorated within as without ; yet a land-shell 

 will doubtless receive a larger share of the solar 

 radiations than a sea-shell. 

 ■ Again, while there is thus abundant proof 

 that an aquatic or even a deep-sea existence is 

 not necessarily incompatible with a rich colora- 

 tion, we find certain groups — the aquatic insects 

 — ordinarily plain in their hues. The water-bee- 

 tles, chiefly frequenting shallow pools and rivers, 

 present ordinarily a dark-olive, black, or brown 

 coloration, relieved at most with rusty yellow, 

 and those of tropical climates show little, if any, 

 preeminence in this respect over their allies from 

 colder regions. But these beetles, be it noted, 

 if devoid of splendor, are not etiolated. The 

 water-scorpion, water-boatman, and other aquatic 

 Hemiptera, though living rather on than in the 

 water, and fully exposed to light, are also re- 

 markably plain in their coloration. 



We have repeatedly referred to nocturnal ani- 

 mals ; but it will be observed that in the higher 

 forms of life the common views concerning their 

 dominant colors scarcely hold good. Thus the 



