112 GUIDE TO THE FOSSIL INVERTEBRATE ANIMALS. 
Gallery 
VIII. 
Table-case 
18. 
Table-ease 
17. 
Wall-ease 
lie. 
Wall-cases 
10 & 11 . 
Schmidtia from the Upper Cambrian of Russia; a mass of 
Lower Llandovery sandstone with Pentamcrus ohlonyiis; 
groups of Conchidinm Aylesfordi from the Aymestry Lime- 
stone, of its ally Sicherella galeata, and of Atnjpa rcticidaris 
from the Wenlock Limestone of Dudley; blocks of Jurassic 
Age with Aidacuthyris and various species of Pdiynchonella ; 
and slabs of Middle Lias, Great Oolite, and Corubrash, with 
their characteristic brachiopods. 
The classification adopted in this Department is that used 
in the English edition of Von Zittel’s ‘ Paheontology.’ Tliis 
is based on the supposed evolution of the group, and may be 
followed in the Wall-cases, where the fossils from foreign 
localities are arranged in zoological order, beginning with 
the top shelf and following its whole length from left to 
Fig. 58. — Types of Brachiopod Orders, a, Order Atremata, the Cambrian 
Iphidea labradorica, ' one of the simplest forms of brachiopod shell, b, 
Order Neotremata, the Ordovician Orbiculoidea lainellosa, the j>edun- 
cular valve, showing the delthyriiim, which has become surrounded by 
the valve and partly filled in from underneath by a shelly deposit, 
c, Order Protremata, the Ordovician Clitambonites Yerncuili, soon 
from the side of the brachial valve, above which is the lofty hinge-area 
of the peduncle valve. The delthyrium is covered bj' a single pseudo- 
deltidium, through which the peduncle passed by the foramen. 
right, and continuing on the middle and bottom shelves in 
the same manner. By attending to this, the genera men- 
tioned in the following account will readily be found. 
In those Bnichiopoda that appear to be the simplest and 
oldest, the shells are not as a rule joined by any hinge 
(Diagram 7). These have therefore been called Inakticulata 
or Ecaruines (c, without ; cardo, hinge) : they include Lin- 
gula, Piscina, Ohohis, Crania, Tnmerdla, and their allies. 
In more advanced forms, such as Orthis, Leptacna, Atrypa, 
2'crchratula, a hinge is developed at the hinder end of the 
shell (Diagram 4), and these have been called Articulata or 
Testicardines {testa, shell ; cardo, hinge). As chissificatory 
divisions, however, these are not altogether satisfactory, for 
the Articulata are necessarily derived froiii the Inarticulata, 
and intermediate forms are not rare. 
