756 THE AMERICAN NATURALIST.  [Vor. XXXIX. 
apex pointing dorsally," but there are no examples of its frequence 
given and in looking through the figures carefully but two cases in 
over a hundred show the apical angle in a position which may be 
considered as pointing dorsally in relation to the axis of the newly 
added column. 
On the whole Miss Klem's paper instead of in any way disproving 
the views originally worked out by Jackson and Jaggär seems, in so 
far as it goes, to be a confirmation of them when they are reduced 
to equivalent terms. 
The bibliography includes works that have only a bare mention of 
the Echini, as Zittel's Geschichte der Geologie und Pal«ontologie, 
while certain others are left out, the most prominent noted being 
Alexander Agassiz's “Revision of the Echini.” 
In the systematic treatment there are a number of statements 
which are open to criticism. On page ı is the statement that “all 
the Palzozoic Echini belong to the C/uss Cidaride” (italics are mine). 
On page ro the class is given as Echinoidea. Also on the same 
page is given a list of the prevailing characters on which the classifi- 
cation is based. In these the number of columns in the interambu- 
lacrum is left out but is nevertheless used in all the descriptions. 
The number of columns in the ambulacral areas and the number of 
pores are considered as two of the most important characters. This 
latter portion is due possibly to the surprising statement made that 
Palzechinus has four pores in each ambulacral plate. As given in 
the generic description Palzechinus has but two columns of ambu- 
lacral plates, but under P. /acazei Julien (page 34), primary and 
secondary plates are spoken of and one pair of pores is given with a 
question. Such a condition is in line with the accepted idea that all 
the Palaeozoic Echini have a single pair of pores to each ambulacral 
plate. 
Frequently the generic description does not.agree with the char- 
acters given under the various species. For example, Lepidesthes 
is stated to have ten columns of plates in each ambulacral area. 
Five species are given, the first with 18 to 20, the second with 10 or 
12, the third with 8 or 9, the fourth with 10, the fifth with aa A 
summary would give 7 to 20 instead of ro. In Lepidechinus the 
number of interambulacral plates is given as 9 to 11. But two 
species are given, the first with 8, the second with 7 to 9 columns of 
plates in this area. Many other instances might be pointed out but 
these suffice to show that the statements given in this work should 
be carefully confirmed before being accepted. 
J. A. CUSHMAN. 
