8() GUIDE TO THE FOSSIL INVERTEBRATE ANIMALS. 
Gallery 
VIII. 
Table-cases 
25 & 24 . 
Between 
Wall-cases 
14 & 15 . 
Wall-case 
14 . 
Table-cases 
24 & 23 . 
Wall-cases 
13 & 14 , 
& adjoining 
pillars. 
iiients i-eferred to the wide-spread genus Olcndlus and other 
genera. Trinuclcus, with ornamented head-shield, is a charac- 
teristic Ordovician genus. As(q)hns tyrannus and Ogygia 
Buchi are common in the Lhindeilo Flags of the same 
Epoch. Hlaemis, witli smooth head-shield and pygidium, has 
even lost the axal furrows from tlie thora.x, and forms 
a strong contrast to the spiny Acidas-pis or the tuberculate 
Encrinurus of Wenlock'ian age. Calymmenc Blumenbachi 
is “ the Dudley Trilobite,” ami to its coiled individuals is 
due the name of the genus (“ cov(ired up”). Ilomalonotus 
is another form devoid of ornament and losing its furrows. 
In Spliaercxochus, Deiphon, and Btaurocephalas (Fig. 40 c), 
the swollen glabella is a remarkable feature. Amoim 
1 Devonian trilobites note the fan-shaped pygidia of Bronteits 
and the tripartite head of Trimcroaphalas. The three 
Carboniferous genera Griffithides, Phillipsia, and Brachy- 
metopus are well represented. 
In the foreign collection one may notice slabs from the 
Cambrian of China covered with “ petrified swallows,” as 
the Chinese call these remains of Htcplianocare, Drepanura, 
and Agnosius (Plate V). Here are fragments and a restora- 
tion ol the huge Asaphm mcgistos from the Ordovician of 
Ohio. The Bohemian collection obtained from J. Barrande 
is particularly valuable. Among the Cambrian genera one 
should note Btyclioparia and Sao ; among the Ordovician, 
Olenus (Fig. 40 h), Isotelus, the large-eyed Aeglina, the deeply 
incised pygidia of Arcia, and Calymmene Tristani whicli 
marks a horizon of Llandeilian age. Calymmene senaria is 
the species in which Walcott discovered the appendages 
by means of cross-sections. Of Silurian genera, BroUvs, 
Aretlmsina, and Rarpes, from Bohemia, should be noticed. 
The Devonian series includes large pygidia of Bronteuti from 
Bohemia, and several trilobites from South Africa. 
Class ARACHNIDA. 
In this Class, as already exidained, we include the 
MEROSTOMATA. First in this division comes the Order 
Eurypterida^ whose structure may best be studied in the 
exhibited model of Euryptcrus (Fig. 41) as well as in the large 
specimens of Bterygotus, Slimonia, and Stylonuvus. ihe 
segmented body is long, flattened, and divhled into three 
regions. The front one consists of the head and some (? 6) 
