Messrs. T. D. A. Cockerell and W. Porter on Bees. 415 



First joint. Last three. %. 



P. (eneifrons, Ckll 560 400 71 



P. mentzelice, Ckll .560 400 71 



P. biyelovice, Okll 480 350 72 



P. zebrata. Cress 450 350 77 



P. mmtzeliarum, Ckll 400 320 80 



P. ymndiceps, Ckll 320 200 81 



P. semicvocea, Ckll 270 240 88 



Perdita sphceralcece cannot be a Cockerellia, as the claws are 

 cleft in both sexes. Neoperdita^ Ashm., was proposed 

 for just such forms, judging from the diagnosis ; but 

 unfortunately Perdita zebrata, having very differently 

 formed labial palpi, is given as the type species. 

 Pentaperdita, subgen. nov., is proposed for P. alhovittata, 

 which has 5-jointed maxillary palpi, these palpi in the 

 ordinary species having 6 joints. The claws are all cleft 

 in the male, simple in the female. The face-markings 

 are the same in both sexes. 

 Telraperdita , subgen. nov., is proposed for P. sexmaculata^ 

 which has 4-jointed maxillary palpi, and the first joint 

 of the labial palpi excessively long. Claws simple in the 

 female, cleft in the male. Mandibles simple. Abdo- 

 men dark, with light spots. 

 Geoperdiia, subgen. nov., is proposed for P. chamcBsaraclice, 

 Ckll., which has the labial palpi only 3-jointed, i. e. with 

 one long joint and two small ones ; while the maxillary 

 palpi are quite rudimentary, with 1 to 3 vaguely indicated 

 joints. 

 Perditella, Ckll., is a subgenus based on P. larrea;, with its 

 curious venation and toothed cheeks. The maxillary 

 palpi are slender and 6-jointed. P. viarcialis also belongs 

 to this subgenus. 

 Cockerellia, Ashm., may be held to include P. alhipennis^ 

 P. sparsa, P. verhesime, P. lepachidis, and P. utahensis. 

 Philoxanthus, Ashm., seems hardly separable from 

 Cockerellia. 

 Perdita, s. str., can never be certainly determined until new 

 specimens are obtained ; Smith's unique type, with the 

 palpi lost, is cited vaguely from " North America." 

 P. semicrocea resembles Smith's P. halictoides in its style 

 of coloration, and may provisionally be regarded as 

 typical ; but there are other species, e. g. P. chamce- 

 sarachcF^ which are also similarly coloured, but differ 

 greatly in the mouth-parts. 



A new descrijjtion of P. sexmaculata is offered, the original 

 description, from the female only, being rather too brief: — 



28* 



