Rcz'iczv of Recent Geological Lilcratiirc. 389 
according them their true value in anj^ general treatise on echino- 
derni morphogeny. Instead of the starfishes and sea-urchins con- 
stituting the entire program, or "whole show," as they do in the minds 
of the average student and in half of the text-books, here they form 
but the last two of the seven classes recognized, and the length of their 
discussion is in proper proportion. It is sincerely to be hoped that 
similar true values will be given among other classes, whether ex- 
tinct or not. 
The phylum Echinoderma comprises two divisions or grades, the 
Pelmatozoa and the Eleutherozoa. In the first are the classes Cys- 
tidea, Blastoidea, Crinoidea. and Edrioasteroidea. In the second 
grade are the Holothuroidea. Stelleroidea, and Echinoidea. This ar- 
rangement shows the unequal value of the classes and does not ex- 
press their phylogenetic relations. The latter probably would be more 
truly represented, according to Bather, by placing a primitive class, 
Amphoridea, at the base and deducing from it several lines of de- 
scent ; namely, Edrioasteroidea, Anomalocystida, Aporita, Rhombifera, 
and Diploporita. From the Edrioasteroid line, it is supposed, there 
sprang first Holothurians, then Stelleroidea, then Echinoidea. The 
Mastoids are included in the Diploporite line, and from them as a 
fresh development with a new lease of life arose the important class 
Crinoidea, whose discussion occupies, as is wholly proper, nearly one- 
third of the present volume. 
The class Stelleroidea comprises the Asteroidea and Ophiurcidea, 
generally considered as quite distinct. Some recent genera, however, 
and many of the fossil forms show that no clear line of separ.jtion 
can be drawn, though the names are still retained for simple conven- 
ience. 
The usual primary sul)divisions of the Echinoidea into two sub- 
classes, the Palaset-hinoidea and Euechinoidea, have been abandoned 
and the older divisions Regularia and Irregularia adopted. The prim- 
itive ancestral Echinoid is unknown, though it is evident that the first 
forms were small sac-like bodies, with the mouth and arms at oppo- 
site poles and the muscular body supported by a series of angular 
plates, of which five pairs were perforated by pores. The thickening of 
the plates and the consequent loss of flexibility is believed to explain 
the reduction in the number of vertical rows taking place in the passage 
from paleozoic to neozoic genera. c. E. r.. 
Recently Discovered Extinct J'ertebrates froiii Egypt. By Ch.\.s \V. 
Anuuew.s, D. Sc, F. G. S., of the British Museum. (The Geological 
Magazine, September and October, iQOi.) 
Northern Africa has long been regarded with peculiar interest, for 
the reason that the geographical distribution and stage of development 
of many Recent and Ca^nozoic vertebrates, gave evidence that Africa 
was a centre in which they evolved and from which they migrated. 
Through the cfjurtesy of the Egyptian Survey, Mr. Andrews has vis- 
ited the Libyan desert, with eminently satisfactory results. 
The formations extend from Eocene tlu-ough Pliocene, and contain 
