254 The American Geologist, October, lasz 
Billings, -wluch has been referred to Kutorgina by authors. This 
species is shown to be generically distinct from Kutorgina cingulata^ 
and for shells of that type the term Paterina is proposed. The proteg- 
ulum is usually "paterina-shaped," yet in Orhiculoidea and Discinisca it 
is modified by accelerated growth "becoming more circular, and with 
shorter and more arcuate hinge in the ventral valve." 
The author then explains in a clear and concise manner the "modifi- 
cations from acceleration; differences in the valves and genesis of form" 
all of which is of the greatest importance to biologists and paleontolo- 
gists. The "types of pedicle openings" are then considered, of which 
there are four, and these are shown to be of general application to all 
brachiopods. Lyopomata and Arthropomata are each divided into two 
orders. The first into Atremata,\ii whicli the pedicle "in all stages of 
growth emerges freely between the two valves, the opening being more or 
less shared by both," and Neotremata, where the pedicle is "more or less 
surrounded by progressive nealogic growth posterior to the initial hinge." 
Tlie Atremata contain Obolella, Trimerella, Lingula, etc., while the Neo- 
tremata have such genera as Discina, Acrotreta, Trematis, Crania, etc. 
The Arthropomata are divided into Protremata and Telotremata. The 
pedicle in the former "is enclosed in early nepionic stages by shell 
growth; posterior covering (pseudo-deltidium) retained at maturity, or 
resorbed or abraded in nealogic stages, so that the pedicle protrudes be- 
tween the two valves." Types of this order are Orthisina, Strophomena, 
Productus, Orthis, Pe/itaiuerus, etc. The Telotremata are distinguished 
in that the "pedicle opening [is] shared by both valves in nepionic 
stages, usually confined to one valve in later stages, and becoming more 
or less limited by two deltidial plates in ephebolic stages." This order 
contains the RhynchoufUidce, Spiriferidte and Terebratulida\ These 
four orders are again divisible into natural suborders, and to these the 
majority of the names proposed by Waagen will be applicable. 
Pa7't II. treats of the "classification of the stages of growth and de- 
cline." The author gives in a condensed manner all the known embry- 
onic and larvel stages of brachiopods from the ovum to the first shell 
stage. Of these there are six for which he adopts the terminology of 
Hyatt, and gives of each one or more illustrations. For comparison with 
the brachiopode four figures of embryonic stages of Spirorhis borealis are 
added, but the author says "it is not intended by this to indicate a close 
relationship with the cha^topods, for the writer is inclined to accept the 
opinion of Joubin, that the brachiopods constitute a distinct and inde- 
pendent class." 
The larval and later stages of Thecidium, as given by Kovalevski, are 
shown by Dr. Beecher to be genetically related to the Strophomeuidse 
rather than with the Terebratulida;, to which the family Thecidiidte is 
usually referred. Heretofore the Protremata, or strophomenoids, have 
been regarded as extinct with the close of the paleozoic age, but now 
this order is known to have lived from its inception up to the present 
time. 
Much value, heretofore, was not placed on the nature of the covering 
