238 
all reason. The name Centrechinus ought to be a still-born name; 
I most sincerely bope that it will have that fate. 
The large second part of the work, containing the systematic 
description of the Palæozoic Echini does not invite criticism. 
Indeed it appears, at least to one not himself trained in palæon- 
tological work, to be a masterpiece of work. Through Jaokson’s 
work the palæozoic Echini, so important both from a morphological 
and a phylogenetic point of view, have now become some of the 
best known fossils. 
I would only point out that it would have been of no small 
importance if sections of the spines of the different types had been 
given, the structure of the spines being of considerable morpholo¬ 
gical value. Are the spines of Palæozoic Echinoids really so com- 
pletely crystallized as to show not the slightest trace of their 
original structure? This would seem somewhat surprising in view 
of the faet that the spines of Triassic Echinoids have still retained 
very distinet traces of their original structure, as shown by the 
beautiful researches of Bather (Triassic Echinoderms of Bakony). 
There is, however, one point, which strikes me as a peculiar 
mistake. Jack son states (p. 244) he has made the remarkable 
discovery that Aldrovandus in 1618 gave a figure “that is 
recognizable as belonging to Bothriocidaris,” and he even thinks 
he can identify it as Bothriocidaris globulus Eichwald. “It is 
remarkable”, he concludes “that this excessively rare echinoid should 
have been found so early and then lost sight of until recent 
years.” This is a somewhat curious story. Jackson quotes the 
work of Aldrovandus as “De animalibus”. 1618. Frankfort. 
There is no work of Aldrovandus of that little. There is one 
called “De animalibus insectis libri septem” and another called “De 
reliquis animalibus exsanguibus libri quattuor. De Mollibus, Cru- 
staceis, Testaceis et Zoophytis.” The edition of 1618 not being 
found in the Copenhagen libraries, I could only consult the editions 
of 1606 and of 1642. In both editions of “De reliquis animalibus 
