MEMOIR. on 
well disposed towards the whites. But keenly as these detours 
interested him, the excessive heat, insalubrity of the tributaries, ex- 
posure, poor food, hard work, and anxiety, so impaired his health 
that he was glad to return to Santarem.* Thence, “from the 
picturesque, hilly country of the Tapajos, and its dark, streamless 
waters,” he migrated to “the boundless wooded plains and yellow 
turbid current of the upper Amazons or Solimoens,” finally settling 
at Ega, where he stayed four years—varied by many excursions 
into the neighbouring region—going in and out among the people 
as one of themselves, pursuing his way unhindered when once he 
had satisfied their curiosity as to why a man should come so far 
and stay so long merely to collect birds and gaudy butterflies! As 
to these last, the Indians “universally concluded that they were 
wanted as patterns for light-coloured calico-prints.” Scarcely any- 
thing was then known in Europe about the biology of that district, 
and therefore the collections made by Bates aroused great interest, 
“the name of Ega being quite a household word among a numerous 
class of naturalists, not only in England, but abroad, in consequence 
of the very large number of new species discovered” by him, 
and of the information gathered “concerning the structure, habits, 
instincts, and geographical distribution of certain oldest-known 
forms. Upwards of seven thousand species of insects alone were 
found in the neighbourhood of Ega, of which five hundred and fifty 
were distinct species of butterflies.” It is of these last that Bates 
penned the striking and pregnant sentences, which alone suffice to 
place him in the front rank of philosophical naturalists, and the 
value of which justifies repetition here. 
*‘T paid especial attention to them,” he says, ‘‘having found that this 
tribe was better adapted than almost any other group of animals or plants to 
furnish facts in illustration of the modifications which all species undergo 
in nature, under changed local conditions. This accidental superiority is 
owing partly to the simplicity and distinctness of the specific characters of 
the insects, and partly to the facility with which very copious series of speci- 
mens can be collected and placed side by side for comparison. The distinct- 
ness of the specific characters is due probably to the fact that all the 
superficial signs of change in the organisation are exaggerated, and made 
unusually plain by affecting the framework, shape, and colour of the wings, 
which, as many anatomists believe, are magnified extensions of the skin 
around the breathing orifices of the thorax of the insects. These expansions 
* Among Bates’s letters of that period which are printed in the Zoologist is one dated 
June 4th, 1852, in which he sighs for “thermometer, barometer, quadrant,” etc., “all 
quite beyond the means of a poor man like myself” (vol. xi., p. 3897). 
