WORK FOR THE NATURALIST. 
87 
But on this subject, giving us fuller information, Mr. IMivart 
introduces us to new problems. It has been suggested, he tells 
us, that birds were derived from certain e.xtinct reptiles, and 
that these were akin to the fossil Iguanodon. He then continues : 
‘‘ That the iguanodon-like reptiles were in some respects like 
the ostrich and its congeners is not to be denied ; but then the 
ostrich and its allies are not creatures on the road to become 
dying birds, but seem rather to be degraded descendants of 
birds which once tievv. Moreover, the oldest known bird, the 
archaeopteryx, is not at all ostrich-like, but has much more 
affinity with ordinary birds, save as regards its hand and tail. 
Thus the origin of birds is a question still open to dispute, and 
while welcoming gladly light from any side upon the problem, 
we would carefully eschew a hasty' dogmatism on that, as on 
every other subject.” The light for which an accomplished 
naturalist thus asks is what other naturalists should seek to 
supply, and it is not only the relationship of class and class that 
may serve as a subject for their investigations. Instances are 
numerous where the true position of a genus in its own class is 
still a perplexity' to classifiers. Thus the crested screamer of 
South America has been variously assigned to such utterly 
different groups as the rails, the geese, and the ostriches, while 
our own water-ousel, who used to be thought an indubitable 
thrush, is now placed between the fiy-catchers and the tits, and 
there are some who, and not without reasons appealing es- 
pecially to out-of-doors naturalists, would rather consign him to 
,the family of the wrens. 
To take a few more instances from the books before us, of 
things yet to be discovered, why is it that, as Mr. Thomson 
tells us, f the insects of a certain small tract in Brazil tend to be 
blue, and a few miles away to be red ? Whence comes the 
tendency to deck themselves with “eyes” wdiich spangles the 
train of the peacock, the wings of the allied argus pheasant, and 
tail and wings alike of the peacock-pheasant ? j; How is it, again, 
that so curious and complex a piece of mechanism as the fangs 
and venom-bag of a poisonous snake counts for so very little in 
the tale of development, that a poisonous snake is frequently far 
more closely allied to non-poisonous than to other poisonous 
ones?”§ To this may be added the still more puzzling fact that 
the possession of the terrible power which makes venomous 
snakes the most dreadful objects in nature, appears to bring no 
benefit at all proportionable to the cost of manufacture. Mr. 
Hudson, in his Naturalist in La Plata, gives it as his opinion that 
no creatures get so little good towards the struggle for existence 
from a special organ of their own as do these serpents, and it is 
a plain fact that the non-poisonous members of the family are 
far more numerous and seemingly more prosperous. It is even 
* p. 95. 
I Types of Animal Life, pp. 69, 70. 
t p. 49- 
§ Ih., p. 129. 
