iQoS Araneae Ther a phosae of California 211 



authors argue, are not so important as the characters, common 

 to both sexes, placing the genus between Atypoides and Hexura. 

 Altho I have not studied specimens of Brachybothrium, 

 Hexura and At^^pus, and have not seen the genus Scotinoecus, 

 which Simon considers as hnking Brachybothrium to the Diplu- 

 rinae, it seems to me that Simon's Atypidae of 1892 is more 

 worthy of recognition as a family than his limited Atypidae of 

 1903. Accepting, accordingly, the older Atypidae as a family, 

 the group logically admits separation into five natural smaller 

 groups, whether of sub-family or tribal rank is not important. 

 Arranged in the form of a key, these groups may be characterized 

 as follows: 



Spinnerets 4, sternal impressions 4, chelicerae with a rake, no coxal 



lobe, thoracic pit longitudinal Brachybothriuin(l) 



Spinnerets 6: 



Chelicerae with a rake, sternal impressions 6, coxal lobe none or 

 slightl}' produced in male. 

 Coxal lobe none, thoracic pit longitudinal, bulb of male without 



conductor Atypoides (2) 



Coxal lobe apparent in male, thoracic pit round, bulb with long 



slender conductor Aliatypus (3) 



Chelicerae without a rake. 



Coxal lobe small, sternal impressions 2, thoracic pit longitiidinal, 



bulb with a stout spur Hexura (4) 



Mecicobothrium 

 Coxal lobe very large, sternal impressions 8, thoracic pit trans- 

 verse, bulb with long conductor .At3^pus (5) 



Calommata 



One other difficulty that comes up in following Simon's late 

 classification is in regard to his groups Cyrtauchenieae and 

 Amblyocarenieae, of the sub-family Ctenizinae. These groups 

 are separated from each other upon the basis of the relative size 

 o'f the posterior sternal impressions and the relations of these 

 two impressions to each other and to the margin of the sternum. 

 As to these characters, I find that in two of the species of the 

 Ctenizinae found in this vicinit^^ that the young answer the 

 requirements of one group while the adults claim admission to 

 the other group. In truth, the sternal impressions seem to be 

 characters that vary according to the age or size of the individual, 

 at least in some species, and should be used with caution in classi- 

 fication. This point will be taken up further, in the discussion 

 of the species concerned. 



From the number of forms of the Araneae theraphosae des- 

 cribed from California, and with Simon's latest work and Com- 

 stock's recent "Classification of North American Spiders" at 

 hand, it was su]oposcd that the species found about Stanford 



