382 Obituary—John Francis Walker, M.A., ete. 
collection. Spontaneously, too, he enriched many a cabinet. A box 
of specimens would arrive with a kindly note to say that he had 
obtained an interesting series from some locality, and he hoped his 
correspondent would find the enclosed specimens an addition to his 
series. 
‘Although Mr. Walker collected Brachiopoda of all ages and all 
countries, he perhaps paid most attention to British Jurassic species. 
He was the first to find the rare Dictyothyris [| Zerebratula| Morvert 
in England, and one of his earliest papers gave an account of the 
discovery. For many years he spent some portion of the Summer 
on the Dorset coast to work the rich deposits in the neighbourhood 
of Bridport; and he published some papers on his discoveries in this 
district. He also made sojourns in the Cotteswolds; while at other 
times his hammer was busy among the rocks of Yorkshire. Only 
last Summer he made a collecting tour among the Jurassic rocks of 
the Normandy coast, and several of his friends’ cabinets are the richer 
for specimens which he then obtained. All who have had the good 
fortune to jom Mr. Walker in his geological excursions will feel the 
keenest regret that they will no more hear his cheery voice, or be 
able to share his great enthusiasm over the discovery of some fine 
specimen.”’ . 
One of his most attached Yorkshire friends, Mr. G. W. Lamplugh, 
F.R.S., writes :—‘‘ Placidly and unobtrusively, he stood aside to let 
the turmoil pass him, and only those who were privileged long to 
enjoy his friendship—to be among whom I count myself fortunate— 
could appreciate the depth of his knowledge and of his kindliness. 
‘‘In his paleontological studies his aim was toward an ideal 
thoroughness that perhaps is unattainable, and he was always content 
—even, as it seemed to me, too content—to wait for conditions that 
should approach his ideal. Thus, much work of excellent purport 
that he contemplated, and might have done well, because it could 
not be done perfectly remained undone to the end. Although his 
collection of the Mesozoic Brachiopoda—his favourite and lifelong 
study—was probably the most extensive that has ever been made, his 
saying was always—‘ We want more material! We must wait till 
we have sufficient material!’ And it was his philosophical grasp of 
the broader problems of his subject that led him to this attitude, and 
not merely the spirit of the collector. The fundamental principle of 
his method found expression in his favourite dictum: ‘It would be 
good for paleontology if all type-specimens should be destroyed !’— 
and most workers who have striven to follow the recent developments 
of paleontological science will apprehend the truth that underlies 
this paradox. Walker, firmly holding the evolutionary idea to 
which his work had led him, recognized that ‘the true type of 
a species is its centre, where the individuals are most thickly 
clustered and most closely resemble each other,’ and that ‘a named 
figured specimen is only a fixed point’ which may, or may not, 
happen to be near or within the central cluster of the species. Hence, 
he said, no single individual can adequately represent a species, and 
the so-called species based on type-specimens are of unequal value 
and often misleading. 
