148 The American (jieologiKt. Murtii, 1893 
13. C. E. Beecher, 1892. Development of the Bracliiopoda. Part 11. 
Classification of the Stages of (Trowth and Decline. Am. Jour. 
Sci.. vol. XLiv, pp. 133-155. 
14. .fames Hall, 1892. An Introduction to the Study of the Genera 
of Paleozoic Brachiopoda. Pal. N. Y., vol. vtii, pt. i. 
Synonyms are in brevier under the name to which they are referred. 
Au interrogation marl< beforp a name indicates that the family or siiln)nlinal relation 
is in donbt. 
BRACHIOPODA. 
(Cuvier 1802), Dumeril 180G. 
Spirobranchiophora, Graj' 1821 ; Palliobranchiata, Blainville 1824 ; 
Branchiopoda, Eisso 1826 (not Latreille); Brachiopodidje, Broderip 
1839; Branchionopoda, Agassiz 1847; Brachionacephala, Bronn 1862; 
Spirobranchia, Haeckel ; Branchionobranchia. Pjctel 1875. 
Subclass LYOPOMATA, Owen 1858. 
Helietopoda (part), and Sarcicobrachia (part), Gray 1848, King 1850; 
Plenrgpygia, and Ecardines, Bronn 1862; Inarticulata, Huxley 1864; 
Tretenterata. King 1873. 
Order Atremata,* Beecher 1891. 
3[esokaulia, AVaagen 1885. 
1. Family Paterinid^e,! n. fam. 
Paterinn. lieecher 1801. 
2. Family i)w^\A\)X.,X King 1840. 
Obolella, Billings 1801. 
Dicellonuis, Hall 1871. 
Elkania, Ford 1880. 
Neobolns. Waagen 1885. 
? Spondyloholus, McCo}- 1852. 
Obolus, Eicbwald 1829. 
Ungula, Pander 1830. 
Ungulites, Bronn 1848. 
Aulonotreta, Kutorga 1848. 
Acritis, Yolborth 1868. 
Schmidtia, Yolborth 1869 (not 
Bals-Criv. 1863). 
*This order is characterized by the pedicle passing out freely between the valves, while 
in the Neotre.m.^ta it is restricted to one valve emerging through a variously modified 
opening. 
iPaterhin, of the lowest primordial, is the simplest shelled condition of brachiopods 
known. Its growth lines show that it does not pass through distinct stages of growth in 
the shell as do all other families of this class. Nearly all brachiopods begin their shelled 
existence with a paterina-like stage. The protegulum or embryonic shell, of the 
Brachiopoda is minute, and tlierefore usually not observable on mature specimens, but 
where well-preserved young, either fossil or recent, have been accessible it is always 
seen to be present. Inarticulate species or the dorsal valve of articulate forms often 
retain it in the mature condition. The protegulum is homologous with the protoconoh 
of cephalopods and gastropods and the prodissoconch of pelecypods. Paterina, there- 
fore, represents a form of growth common to the protegulum and nepionic stages of the 
majority of brachiopods. 
JThe lingula-shaped shells with obolelloid interiors, the LixoiLEi.i.in.E, are removed 
from this family since it is very probable that from them developed the Lingulii)^. In 
this connection, the writer wishes to state that LiiKiiilella, as here understood, is based 
on L. Citlata Hall, sp., and L. ella Hall and Whitlield. 
The obolelloids are thicker, more calcareous, and rounder shells than the I/INGulell- 
iD.E, and in all probability" gave origin to the Tiumerelliuj;. 
