Paleontological Speculations. — Gratacap. 8i 
fauna well developed skeletons or thickened hard parts (shells, 
carapace, hinges, etc.), we may conclude that the group rep- 
resented has attained functional equilibrium, and has existed 
longer than similar organisms of less physical mass or internal 
■osseous or shelly deposits. The simple and obvious condition 
prevalent in individuals has an adumbrant genetic application. 
While it is unquestioned that favorable conditions, stimuli 
both of health and food, accelerate the deposition of hard 
])arts, yet it is certainly clear that age brings, of necessity ac- 
cumulation of material, both because secretion has acted 
through a longer period of growth, and that in senility the 
turgor of the secreting membranes so increases as to give rise 
to heavier depositions of mineral substances (calcification). 
And it seems a just inference that at the inception of a 
^roup of organisms their physiological relations precede the 
skeletal sequelae of these relations, that if hard parts are se- 
creted in the early stages of an organism's history the func- 
tion of their secretion increases by use, by heredity, through 
time, and the habit of forming them is reinforced and extended 
as the organism is geologically older. It is conceivable that 
the mollusca began in shell-less or almost shell-less organ- 
isms,''- that the acquisition of shell, the elaboration of hinge 
teeth and even the interlaminal deposition of "loops," "arms," 
or internal appendages as mineral or hard parts was slowly, 
with a slowness sensibly reflected in their palaeontological 
phases, consummated. Or, in other words, the appearance of 
well developed hard parts internal or external, skeletal or teg- 
umentary, marked an evolutional climax. This is really an or- 
dinary assumption. The biology of the mollusca, and crusta- 
ceans, and echinoderms shows the secondary and subsequent 
development of the hard parts. They are themselves sympto- 
matic of the finished phases of embryological changes. An in- 
complete power of secretion must have marked the earlier 
phases of histological growth. In the evolutionary process the 
heavier armored, thicker shelled, harder carapaced organisms 
must have followed the more slender fragile and tenuous cov- 
ered animals. 
♦Investigation seems to point to Lingnla as a primal form of brachiopo- 
dous iife. (fJee Die Silifisdien t'l-an'aflen <ler Ostseelands mit Anschluss 
Gotlands, bel Friedrich Baron Hotninobn 'B.^-v^K.Terhandlungen der Rus- 
sisch-Kaiserlichen Mincralogischen Gesselschaft zu St. Petersburg, 1899). Dr. 
Beecher has already furnished the evidence to show that the progenitor of 
the brachlopod phylum was Kutorgina. 
