424 Mr. J. Thomson and Dr. H. A. Nicholson on the 



of Christianity not worth his notice ; but tell him there is a 

 ladder between the highest summit of the Himalaya and the 

 Heavens, on which there are Munis and Rishis going up and 

 down all the day long, and he will say " that's worth believ- 

 ing ! " Belonging to that school which can see nothing satis- 

 factory in a theory so elastic that no human argument can 

 cover it, and nothing so contemptible, in a scientific point of 

 view, as the habit of hastily theorizing, I have not much 

 sympathy with those who are always ready with a cause 

 and explanation for every thing. When facts are discovered, 

 they can be told in a few words ; and the most palpable only 

 should be credited with a deduction like that of the " dawn of 

 life." 



LVTI. — Contributions to the Study of the chief Generic 

 Types of the Palceozoic Corals. By James Thomson, 

 F.G.S., and H. Alleyne Nicholson, M.D., D.Sc, 

 F.R.S.E., Professor of Natural History in the University 

 of St. Andrews. 



[Continued from p. 309.] 



[Plate XII.] 



Genus Amplexus. 

 Amplexus, Sowerby, Mineral Oonchology, vol. i. p. 165. 



Gen. char. Corallum simple, subcylindrical or cylindro- 

 conical, tapering towards the base, frequently tall, and more 

 or less twisted. The epitheca is thin, with encircling lines of 

 growth ; and accretion-ridges are usually more or less con- 

 spicuously developed. Septa delicate and very short, never 

 reaching to near the centre of the calice. Tabula? exceedingly 

 well developed, extending completely across the visceral 

 chamber, and invariably exposed over a wide central area, 

 into which the septa do not penetrate. A septal fossula is 

 present, which is usually formed by a slight lateral depression 

 of the tabula?. Calice circular, moderately deep, with a thin 

 margin. 



The nearest ally of Amplexus has generally been assumed 

 to be Zaphrentis ; and there is doubtless a close alliance be- 

 tween the two. Typical examples of the former, however, are 

 very readily and completely separated from characteristic 

 species of the latter genus by the much more rudimentary 

 condition of the septa and the nature of the septal fossula. 



