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



Firstjoint. Last three. %. 



P. (vneifro7is, Ckll 560 400 71 



P. nienfzelifs, Ckll 5G0 400 71 



P. hirjelovife, Okll 480 350 72 



P. zebrata, Cress , 450 350 77 



P. mentzeliarum, Ckll 400 320 80 



P. yrandiceps, Ckll. . . 320 260 81 



P. semicrocea, Ckll 270 240 88 



Perdita sphceralcem cannot be a Cocker ellia, as the claws are 

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

 tor 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. albovi'ttata, 

 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. 



Teirape)-difa, subgen. nov., is proposed for P. sexnacidata^ 

 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. 



Geoperdita, subgen. nov., is proposed for P. chamcesarachce^ 

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

 one long joint and two small ones j while the maxillary 

 palpi are quite rudimentary, with 1 to 3 vaguely indicated 

 joints. 



Perditella^ Ckll., is a subgenus based on P. larrece, with its 

 curious venation and toothed cheeks. The maxillary 

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

 to this subgenus. 



CocJcerellia, Ashm., may be held to include P. alhipenmsj 

 P. sparsa^ P. verbesime, P. lepachidi's, and P. utahensis. 

 Philoxa7Uhus, Ashm., seems hardly separable from 

 CockereUia. 

 Perdita^ s. str., can never be certainly determined until n&w 

 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. chamoi- 

 sarachce^ which are also similarly coloured, but differ 

 greatly in the mouth-parts. 



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

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



28* 



