Bevieiv of Recent Geological Literature. 253 
■ The work before us represents an inconceivable amount of pains-tak- 
ing labor. The determination of the internal characters of the multitud- 
inous species of Paleozoic bra'hiopods is something from which persons 
less enthusiastic and less gifted than the eminent author might well 
shrink. The work has been in hand more or less continuously for more 
than twenty years. That it is at last practically completed is something 
"for which professor Hall deserves to receive the thanks and congratu- 
lations of paleontologic students. 
The fulness with which each genus is illustrated adds incalculably to 
the value of the volume. 
Development of the Brachiopoda. Part I. Introduction. (Am Jour. 
Sci., vol. XLi, 1891, pp. 343-357, one plate.) Part ir. Classification of the 
■Stages of Growth and Decline. (Ibid. vol. xliv, 1892, pp. 133-135, one 
plate.) By Charles E. Beecher. 
The object of these papers is to apply to the Brachiopoda " the law of 
morphogenesis as defined by Hj^ntt." No one of the classifications hereto- 
fore proposed is established upon fundamental principles but all are based 
on one set of secondary characters for certain groups and another set for 
other sections. The Brachiopoda, until 1883, had only been divided into 
two sections, the Lyopomata and Arthropomata of Owen, or the Inarticu- 
lata and Articulata of Huxley. When we consider that there are about 
5,000 known species of brachiopods, arranged in over 270 genera, occur- 
ing in the oldest uudoubted fossiliferous rocks and down to the present 
time, it certainly seems as if Ihe class should be capable of further 
separation into large groups or orders besides those based upon the 
presence or abseoce of an articulating process. In that year. Dr. 
Waagen in his great work on the Brachiopoda of the Salt Range of 
India, further divided each section into three suborders. While this 
classification brought together, more or less correctly, families having 
relations to each other, yet no far reaching attempt was made to show 
the genesis of the class in the application of the principles of phylogeny 
and ontogeny. In the above mentioned papers Dr. Beecher has applied 
the ''principles of growth; acceleration of development; mechanical 
genesis and geologic sequence of genera and species." The develop- 
ment of ancient species in their adult condition represents nealogic 
(youthful) or nepionic (young) stages of later forms. 
The first or embryonic shell is alike in all Brachipoda, except where 
. modified by accelerated development, it having been observed by the 
author in about forty genera, representing nearly all the leading fami- 
lies of the class. This, the first shell stage, he has termed the "proteg- 
ulum" and is homologous with the "protoconch" of Owen in cephalo- 
pods and gastropods, and the prodissoconch of Jackson in pelecypods. 
The protegulum is "corneous and imperforate, semi-circular or semi- 
elliptical in outline, with a straight or arcuate hinge line, and no hinge 
area." The "prototype preserving throughout the development the 
main features of the protegulum, and showing no separate or distinct 
stages of growth " is found in the early primordial Ohohis labradoricus 
