94 



BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



Following is a comparison of dimensions by ratio. The first col- 

 umn represents the ratio of the breadth of the cephalothorax between 

 the spiracles to the distance between the mandibles; the second rep- 

 resents the ratio of the breadth of the head to the distance between 

 the mandibles; the third the ratio of the breadth between the spira- 

 cles to the breadth of the head; the fourth the ratio of the breadth 

 between the spiracles to the distance from spiracle to apex.. The 

 species are arranged in the same order as in the preceding table. 



Species. 



solidulx 



cornii 



vicinx 



grxnicheri . . 



crawfordi 



salicifloris. . . 

 advarians... 

 californica . . . 



imitatrix 



cressoni 



multiplicatx 

 nubecula... 



claylonix 



hippotes 



swenki 



viereeki 



bipunclatx. . 

 subcandidx. 



nasoni 



sparsipilosx . 



bruneri 



hartfordensis 

 polemonii.. . 

 oklahomx ... 



Cephalothorax 

 to mandibles. 



(5):(3)::-:l.<> 



6.61 

 -7.66 

 6.68 

 7.12 

 7.13 

 7.00 

 6.06 

 7.58 

 7. 63 

 7.16 

 7.12 

 7.41 

 7.70 

 6.28 

 6.27 

 ti. 75 

 6.45 

 7.30 

 7.77 

 7.30 

 C.63 

 6.14 

 7.00 

 9.57 



Head to 

 mandibles. 



(4):(3)::-:l. 



Cephalothorax 

 to head. 



(5):(4)::-:l. 



3.66 

 4. 07-4. 60 

 3.81 

 4.34 

 3.93 

 4.35 

 3.46 

 4.83 

 4.45 

 3.87 

 4.08 

 4.00 

 4.50 

 4.00 

 3.93 

 4.16 

 3.90 

 4.50 

 4.33 

 4.40 

 4.84 

 3.90 

 3.91 

 5.52 



1.80 

 1. 66-1. 84 

 1.75 

 1.88 

 1.81 

 1.60 

 1.75 

 1.56 

 1.71 

 1.84 

 1.74 

 1.85 

 1.71 

 1.77 

 1.59 

 1.62 

 1.65 

 1.62 

 1.78 

 1.05 

 1.36 

 1.57 

 1.06 

 1.73 



Breadth to 

 length. 



(5):(2):: 



1.32 

 1. 34-1. 35 



1.40 

 1.56 

 1.55 

 1.42 

 1.41 

 1.51 

 1.55 

 1.53 

 1.52 

 1.57 

 1.49 

 1.77 

 1.65 

 1.50 

 1.37 

 1.58 

 1.45 

 1.53 

 1.79 

 1.40 

 1.32 

 1.43 



<* These ratios refer to the numbers at the head of the preceding table. 



This study of comparative dimensions is sufficient to show any one 

 that the species may be easily distinguished. To facilitate identi- 

 fication the writer has illustrated a female of each species and given 

 the mandibular character prominence. No relationship can be found 

 between the parasites and the artificial subgenera designated for 

 Andrena by Robertson. 



i. STYLOPS MELITT-ffi Kirby (1802). 



Stylops kirbii Leach, 1814. 

 Stylops haworthi Stephens, 1829. 

 Stylops melittse Saunders, 1872. 



Host. — Andrena nigro-aenea Kirby; England, Germany, Hungary 

 (fig. 2, no. 14; pi. 2, fig. 4). 

 The following description is drawn from Kirby 's original description : 



