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HARDWICKE'S SCIENCE -GOSSIP. 



thing but fish, while watching him in the river; 

 and when kept in a tank, he left a large crawfish 

 {Cambarus affiiiis) severely alone, after having taken 

 one little smell and received one big tickle on the 

 end of his nose. Of his breeding habits we have 

 now nothing to say, but will keep on the look-out 

 next spring for this " Mud-devil," and if he sur- 



waters. If this was the case with the extinct forms, 

 some of which belong to existing genera, then their 

 presence throws great light on the circumstances 

 under which some of our limestone beds were 

 formed. Wenlock Edge, in Shropshire, is, accord- 

 ing to Professor Owen, nothing but an ancient 

 coral reef, in which the principal fossil corals are 



Fig. I'a. "Mud-Devil" {Menopnma Alleghaniensis), 



vives over winter and withstands the fresbets with 

 their miniature glaciers, perhaps we will learn some- 

 thing new concerning him, as twisting, squirming, 

 jumping, he beslimes the green banks of little Belle 

 brook, or deeply diving, lie stirs up the sand from 

 the bed of the beautiful Delaware. 



NOTES ON EOSSIL CORALS. 



THERE are few objects obtainable by the geolo- 

 gist which possess greater interest than fossil 

 corals ; not only because the ancient forms difl'er 

 structurally from modern, but also because they 

 testify so plainly to ancient physical geographical 



Fig. 176. Fossil Coral (Zaphrentis cornicula). 



conditions. We know, for instance, that except in 

 the case of the so-called single corals, of which our 

 own recent Caryophjllum cyathus, or " Cup-coral," 

 is an example, all the compound forms affect shallow 



Favosites pohjmorpha and the beautiful " Chain- 

 coral" {Ucthjsites catemdatus), so called on account 

 of the chain-like manner with which the tube-mouths 

 are connected. In this respect it resembles the 

 recent Music-coral {Tublpom miisica), which, how- 

 ever, is placed in the order Alci/onana. • • 



Fig. 177. Fossil Coral {Cyathophijllum hexagonum). 



The extinct compound corals are grouped into a 

 separate order called Rugosa, and are distinguished 

 from the recent by a generally lower organization. 

 In some respects they form an intermediate group 

 between the true corals and the Alcyonaria. Zaphreu- 

 tis — a genus common in the Carboniferous limestone 

 —was evidently solitary, like our British "Cup- 

 coral." There is a difference, also, in the number 

 of plates radiating from the centre of the fossil and 

 the recent corals. In one it is a multiple of four. 



