141 



are the helices and their allies, '2,500 species, mostly banded, very few- 

 spotted ; dolium, twenty-five species, some of them very conspicuously 

 banded. 



The cowries, on the other hand, are remarkable for solidity and 

 strength ; comparatively few of them are banded. I cannot, however, 

 omit to mention a somewhat remarkable change of pattern in the cowry. 

 When the animal is young, and the shell is thin and fragile, the pattern 

 upon the shell is distinct]}^ barred or banded ; but when the same 

 animal becomes mature, and the shell is heavy and strong, the banded 

 pattern is obliterated, and the shell is spotted ; a change for which 

 there is no apparent physiological cause, but which is common to many 

 of the species. 



Simple bands or spots, although amongst the most common colour 

 patterns, are by no means the most remarkable. The ocellate spot, so 

 frequently found on the -wings of lepidopterous insects and on the 

 plumage of birds, is singularly interesting on account of the position of 

 the pupil or brightest portion of the spot, which is not in the centre of 

 the surrounding annulus, the whole spot being eccentrically shaded in 

 the exact manner in which an artist would represent a hemisphere 

 lying on a table before him. Is the ocellate spot indeed a specimen of 

 nature's pei'spoctive drawing, adorning her exquisitely tinted ground- 

 work with the image of a jewelled stud in high relief? 



I have endeavoured to show, with respect to the colours, natural 

 productions complete in themselves. 



1st. There is invariably a careful preservation of tone. 



2nd. The tints are disposed so as to harmonize with each other. 



3rd. That where an intense effect is desired, combinations of 

 colour are employed, which, under ordinary circumstances, would be 

 disagreeable. 



4th. That varied patterns formed after the same type distinguish 

 species which belong to the same natural order or group. 



5th. That it may be possil.'le to decypher colour patterns. 



6th. That certain indications seem to suggest the possible meaning 

 of simple bands, spots, and the ocellate spot. 



We see much of nature's painting, but are seldom permitted to 

 examine her pencil. The colours of birds and animals are formed so 

 gradually that the process by which they are elaborated quite evades 

 our notice. In shells we are acquainted with the organ which in 

 certain species paints the pattern. In the cowry, two soft pliant lobes, 

 called the mantle, spread themselves from the aperture to the back of 

 the shell, the dorsal line, so common in this specios, indicating where 

 tlie two lobes meet. It is most wondrous indeed that so soi't and 



