ANNIVERSARY ADDRESS OF THE PRESIDENT. XXV 



those in the limestone of Plymouth are not very easily discovered | 

 but the geologists of those days had not yet found out that it is not 

 in the fresh fracture of a crystalline limestone, but on its weathered 

 surface that we are to search for the included fossils with most hopes 

 of success, particularly as regards Corals. It was this Vy'hich first 

 revealed the secret to Mr. Hennah : he tells us, that on the weathered 

 surface of large blocks he found " the varied figures of Madreporites, 

 which left no doubt on his mind respecting the nature of their con- 

 tents," and thus encouraged, he succeeded in obtaining "unquestion- 

 able proofs" that the limestone enclosed "very numerous and striking 

 varieties of organized remains of marine animals*." To him, there- 

 fore, the science is indebted for the evidence of this fact, and for the 

 first delineation of the fossils. Mr. Hennah's claims upon the con- 

 sideration of geologists, nevertheless, do not rest on his published 

 memoirs, as to his unremitted exertions are due the preservation and 

 accumulation, in one series, of the various organic remains which the 

 public works conducted during his long residence in Plymouth laid 

 open. These collections were most freely rendered available to 

 science, and the loan of them to Mr. Lonsdale, Professor Sedgwick, 

 and Sir R. Murchison, afforded one of the principal sources for 

 determining the relative geological age of the Devonshire limestones. 

 That valuable collection vvas on his death presented by his son, the 

 Rev. William Hennah, Incumbent of East Cowes, to this Society ; 

 the greater part is now in our possession, and the Corals are now at 

 Bath under examination by Mr. Lonsdale, from whom we shall at 

 no distant period receive what will doubtless be a most able report 

 upon them, and which will greatly enhance their value. As the col- 

 lection contained many duplicates, Mr. Lonsdale, who is ever ready 

 to make great sacrifices for the advancement of science and for the 

 interest of this Society, notwithstanding the very delicate state of 

 his health, went at the request of the Council from Bath to Ply- 

 mouth, and made the selection ; this donation has been perhaps the 

 most valuable acquisition in our Museum during the last year. 



But I should not do full justice to Mr. Hennah, were I to confine 

 my observations to his merits as a palseontologist. I had not the 

 pleasure of his personal acquaintance, but Professor Sedgwick, who 

 knew him well, has supplied me with some particulars, from which 

 it may be fairly inferred, that if Mr. Hennah had been able to travel, 

 he would, in all probability, have been a still more extensive contri- 

 butor to the progress of Geology. I will give the information with 

 which Professor Sedgwick has favoured me in his own words : — " I 

 first saw Mr. Hennah at Plymouth in 1819; at that time he had 

 made a fine collection of the neighbouring fossils, and he had a good 

 general notion of the position of the Plymouth limestone, viz. that 

 it was over the slate between Plymouth and Dartmoor, and under 

 the slates farther south. Like all older geologists, he believed that 

 the granite was primitive, and that the Cornish slates were among the 

 oldest stratified rocks of the world ; hence he had not a true notion 



* Succinct Account, pp. 6, 20, 30. 



