(' lass ip' cat ion of the lii'aehiopoda. — Schuchi'ii. 148 
was made by writers to divide the Brachiopcxia into other orders 
than Lyoponiafa and Arf/iropomafa until 1883, when Waagen" 
published his great work on the fossils of this class from the Salt 
Range group of India. He found it '-absolutely necessary' to fur- 
ther divide the Lyojmiuata and Art/(roj>omaf(i each into three subor- 
ders. The basis for these suborders has no underlyingjjrinciple 
of general application, yet the divisions are of permanent value, 
for each contains an assemblage of characters not to be found in 
any of the others. Waagen's genealogy of the Arfhrojttonata, 
with Orthis as the prototype, falls at once to the ground, since 
HalP* has recently shown that probably no true Ortlns exists in 
the primordial. The orthis-like shells of the primordial are forms 
either with a deltidium or a spondylium (the interior spoon-shaped 
plate of pentameroids) or l.>oth plates present in the same individ- 
ual. Ephebolic Orthis do not possess either structure, but during 
nepionic and earl}- nealogic growth may develop a deltidium. 
which, before maturity is attained, is lost by abrasion or con- 
cealed by the incurvature of the ventral beak. LiiK/ahi, on the 
other hand, is usually regarded as the prototype for all brachio- 
pods, but this is impossible, since a number of inarticulate genera 
flourished for ages before Linyula was developed. 
No classification can be natural and permanent unless based on 
the historj' of the class (chronogenesis) and the ontogeny of the 
individual. However, as long as the structure of the early pale- 
ozoic genera remained practically unknown and the ontogeny un- 
touched, nothing could be attempted of a permanent nature. 
Recently a work'* upon paleozoic brachiopods has been published, 
in which many of the early genera are clearly defined, so tliat 
their structures and geologic sequence are now more accurately 
known. The ontogenetic study of paleozoic species was initiated 
two years ago by Beecher and Clarke," and the results combined 
with those derived from the development of some recent species, 
and published by Kovalewsky, Morse, Shipley, Brooks and others, 
confirm the conclusions reached through chronogenesis. More- 
over, the application b}' Dr. Beecher.''- '•' of the law of morphogen- 
esis as defined by Hyatt,"- '" and the recognition and establishment 
of certain primary characters, have resulted in the discovery of :i 
fundamental structure of general application to the classification 
of these organisms. It has for its basis the nature of the pedicle 
opening and the stages of shell growth. On this the author has 
