these animals are principally Rats, Beetles of various species, 

 Bats and Crustaceans. Now I need hardly remind you, that 

 although Bats and Beetles were once popularly supposed to 

 be blind, it was only a vulgar delusion, and consequently the 

 connection of these blind animals with the outer world 

 becomes of extreme interest, in connection with Darwin's 

 theories as to the origin of species. His idea is that their 

 ancestors wandered into these caverns in remote ages, that 

 generation after generation was born and died without ever 

 seeing light, so that the disuse of the organs of sight grad- 

 ually led to their entire suppression, and this seems the more 

 reasonable because one kind of rat was discovered, which 

 though quite blind in the daylight, had eyes which were 

 enormously developed and with which it could very probably 

 see in the dark, while others had the optic nerve developed, 

 though there was no vestige of external eye, and some of the 

 beetles had their antennae enormously developed, as though 

 to compensate for the loss of vision. The whole theory of 

 the origin of species is one of enthralling interest. We all 

 know that many animals existed in remote ages, which have 

 no representatives now ; but we scarcely reflect that in this 

 our day species are dying off the face of the earth, several 

 even have become extinct during the last 20 years, and Gosse 

 estimates the loss in this way at no less than one species for 

 every year. Thus it would appear that species have their 

 allotted time for existence, just as individuals have theirs, — 

 thus a Fly may have a span of life for a few days, a Raven or 

 an Elephant of almost centuries — so the species of Irish Elk, 

 or the species of the Mastodon may have reached their allotted 

 span in the Tertiary Era ; whereas that of the Dodo, the 

 Great Auk, &c. may have expired only recently, and that of 

 the Wolf, Beaver, &c. may be quickly approaching. The 

 question then arises are fresh species being created ? Are 

 some of our newly discovered animals really only newly 

 created ? We know that with individuals the death-rate 

 is pretty nearly counterbalanced by births. Does this law 

 hold good with species ? How many are and have been for 

 ages extinct ? There was the huge Dinotherium that wan- 

 dered in the half-drained Swiss valleys and in the swamps of 

 Germany, a monster larger than the largest Elephant, a body 20 

 feet long and legs 10 feet high; a head something like that of 



