2 24 Alexander PctrunkcvitcJi, 



SUC-ORDER MYGALOMORPH^. 



Spiders with an unsegmented abdomen and two pairs of lungs. 

 Articulation of chelicerae such that the fangs move in a plane par- 

 allel to the plane of symmetry. 



This sub-order comprises two families, Aviculariidre and 

 Atypidae. 



FAMILY AVICULARIID^. 



Usually four, sometimes two spinnerets. (Anterior spinnerets 

 belonging to the fourth abdominal somite and found in Atypidae 

 and other spiders are missing in Aviculariidae.) Eyes eight or 

 six, usually situated on an elevation and forming a compact group. 

 Anterior median eyes alone of the diurnal type. Coxse of pedi- 

 palps without maxillary lobes. 



A very large family comprising almost all recent Theraphosid 

 spiders and practically limited to the equatorial and tropical belts. 

 In this country the family is represented by some thirty species, 

 most of which are distributed through the southern states and 

 California. One species was found in Virginia, another in the 

 Indian Territory. I have a single specimen of a species new to 

 science and as yet unpublished from Indiana. 



The separation into sub-families and genera of spiders belong- 

 ing to the family Aviculariidae is based on the following charac- 

 ters: structure of the tarsi and number of claws, number and 

 structure of spinnerets, presence or absence of a rastellum on the 

 chelicerte, number of eyes and configuration of eyegroup, shape 

 of carapace and sternum. 



Being unable to place the single species of Theraphosid spider 

 from Florissant under any of the numerous recent genera, I pro- 

 pose the new genus Eodiphtrina for Tertiary forms more or less 

 related to the recent sub- family Diplurinre. 



Genus Eodiplurina, new. 



Theraphosid spiders with two pectinated claws and two pairs of 

 spinnerets of which the posterior ]mir is three jointed and much 

 longer than the anterior pair, (ienotyj^e : 7f . eoekerelli. 



