274 ROYAL SOCIETY OF CANADA 
This little creature is clearly a hexapod and can best be referred to 
the Thysanura. as the three segments of the thorax are separate ; there is 
a spring (elater) to the abdomen, and there are no traces of wings. It 
has not the compactness of body of the modern Springtail, but in its 
elongated form it approaches the species of Lepisma or Bristletails ; 
however. these have more numerous segments to the abdomen than 
Podurites ; and the strong stylet or spring of the latter is a distinguish- 
ing feature, that precludes us from placing it in Lepisma: the form and seg- 
mentation of the abdomen is thus intermediate between Podura and 
Lepisma, but sufficiently distinct from either to warrant the establish- 
ment of a new family for which I would suggest the name Poduritidæ.! 
ARACHNID A. 
According to Dr. S. H. Scudder (188!) two hundred and fifty species 
of Arachnids have been described from the Tertiary deposits. Of these 
one hundred and ninety are true spiders, while the remainder are Acarina 
(mites), Ophiliones (11 species), Chernitidæ.( 9 species). Of these insects 
nine-tenths (1886) have been preserved in amber, leaving only a quarter 
of a hundred species from other sources as representatives of this great 
division of the ancient insect world when Dr. Scudder commenced his 
studies on the insect fauna of Florissant. This fauna is contained in 
lacustrine clays, and the result of Dr. Scudder’s study of the insect re- 
mains contained in it—if we omit from consideration the Arachnids of 
the European amber—more than doubled the number of Arachnids known 
as fossils up to that time. 
While this was the relative number of the European and American 
Tertiary spiders up to this time, important additions were also being 
made to our knowledge of the Paleozoic Arachnids, for in the succeeding 
decade spider-like animals began to be found in the coal measures and 
among them several peculiar types, differing from any known in the 
later ages. Among these were the Anthracomarti of Karsch, differing 
widely from modern spiders, and established as a separate order by that 
author. 


| Since the above paper was written another Thysanuran has been found, more 
remarkable than Podurites—that is, more difficult of comparison with any other 
modern form. While exhibiting the separate segments which are found in the 
thoraces of the Thysanurans, its head can only be compared with that of Scudder’s 
genus Planocephalus, from the Oligocene beds of Florissant, or with certain suctorial 
Hemiptera. Perhaps it might be said that the existence of such a form as Plano- 
cephalus, best explains the peculiar structure of the new type, for it can be referred 
to the Thysanurans only on the same general considerations as have governed Dr. 
Scudder in so referring that genus. 
