OF THE CARBONIFEROUS XIPHOSUROUS FAUNA. 
157 
From the Crustacea the Podostomata differ in the lack of functional antennze and mouth 
parts ; in the brain innervating the eyes (compound and simple) alone; in the shape of the head 
and of the pygidium or abdominal shield, and in the arterial coat enveloping the ventral nervous 
cord. 
The Podostomata are divided into two orders : 
I. Merostomata with three suborders, Xiphosura, Synziphosura, and Eurypterida. 
Il. Trilobita. 
Fig. 
All the Cen on this plate drawn by Dr. J. S. Kingsley, with corrections by the author. 
Explanation of Plate ¥. 
. Cyclus americanus Pack. X#. la, lateral view restored. X?. 
. Dipeltis diplodiscus Pack. Natural size; 2a, the same restored. X#. 
. Prestwichia dane Meek. Natural size; restored; dorsal view. 
. Prestwichia dane Meek. Natural size; partly restored; ventral view. 
. Prestwichia longispina Pack. Partlyrestored. Xj. 
. Belinurus lacoei Pack. Partly restored. X2. 
Explanation of Plate VI. 
Fig. 1. Prestwichia dane, showing the limbs; 1a, the reverse. 
Fig. 
Fig. 
Fig. 
2. 
3. 
4. 
Prestwichia dane, showing the interior; 2a, the same, another specimen. 
Prestwichia longispina, natural size. 
Cyclus americana, natural size; 4a, reverse of the same. 
From photographs taken by Mr. R. L. P. Mason, Providence, R. I. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
All the figures of natural size and from photographs taken by Mr. F. O. Draper, Pawtucket, R. I. 
1 
2 
3. 
4 
5 
6. 
Explanation of Plate VII. 
. Paleocaris typus M. & W., natural size. 
. Paleocaris typus M. & W., natural size. 
Anthrapalemon gracilis M. & W., carapace laterally flattened. 
. Anthrapalemon gracilis M. & W., from a small specimen without the carapace. 
. Anthrapalemon gracilis M. & W., carapace wanting. 
Antlerapalemon gracilis M. & W., carapace wanting. 
