Palaeozoic Arachnida of North America. 



31 



been preserved. Such a method is certainly open to grave criticism, 

 but it is the only possible one. The text figures i — 4 showing the 

 external characters of recent scorpions will help the understanding 

 of the incomplete remains of Palaeozoic specimens. 



The scorpions have been divided into two sub-orders, the dis- 

 tinguishing character being the presence or absence of two claws on 

 the walking legs. 



Fig. 3- 



Fig. 2. 



Fig. I. Fig. 4. 



Figure i.—Opisihacanihus elatus (Gerv.), from the West Indies, ventral 

 surface of a gravid female. Figure 2. — Same, dorsal surface of cephalo- 

 thorax and anterior seven abdominal segments. Figure -i. — Centrums 

 junceus (Herbst), from Cuba, end of tarsus with walking spine, two claws 

 and dorsal lobe. Figure 4. — Same, viewed from below to show the position 

 of the dorsal lobe. 



LIST OF DESCRIBED SPECIES OF SCORPIONS 



SUB-ORDER APOXYPODA. SILURIAN SCORPIONS 

 Tarsi terminating in a sharp point, without claws. 



Family Palaeophonidae Thorell and Lindstrom 

 Genus Palaeophonus Th. and L. 1884. 

 Genotype P. nuncins Th. and L. 



