Plate V 



Fig. 1. Primitive Generalized Diagram of Pselaphid mesosternal and meta- 

 sternal field. P, prepectoid area; MOS, mesosterniim ; MOES, meso- 

 episternum; MOEP, mesoepimeron ; MOCC, mesosternal ooxal cavi- 

 ties; MES. metasternum; MEES, metaepisternum. 

 I, Prepectoid foveae. IV. Lateral mesocoxal foveae. 



II, Lateral mesosternal fovene. V, Posterior mesocoxal foveae. 

 Ill, Median mesosternal foveae. VI, Metasternal foveae. 



Fig. 2. Sonoma iRafonus) tolulae (LeConte). 



Mesosternal and metasternal field. Legend as in Fig. L Note that 

 this species has eleven foveae, that is, all are present save the meta- 

 sternal foveae, which are medianly fused into one fovea. 



Fig. 3. Euplectus iPycnoplectus) interruptus LeConte. 



Mesosternal and metasternal field. Legend as in Fig. 1. Of the three 

 pair of foveae present (II, III, IV), note that two are pubescent 

 (II, IV), indicated diagrammatically by short straight lines in the 

 mouth of the fovea. Foveae III externally might pass unnoticed, the 

 foveal mouth is so inconspicuous. Fig. 3a. Shows Foveae II and III 

 in a transparent integument, to illustrate the characteristic whorling 

 of the walls of the foveae. Note (a) in Fig. 3, of attachment to 

 mesothoracic wing. 



Fig. 4. Trimiomelba diibici (LeConte). Male. 



Mesosternal and metasternal field. Legend as in Fig. L Two pair of 

 foveae present (II, V) , while III is median and unpaired. The foveae 

 are all represented as transparent, so that the whorling of their walls 

 can be observed ; II are remarkable in size, and in cleared slides these 

 foveae meet in the midline, above median III, but do not inter- 

 communicate. Note the metasternal furca (MEF) indicated by 

 dotted lines. 



Fig. 5. Tmesiphorus costalis LeConte. 



Mesosternal and metasternal field. Right side of figure presented 

 with transparent integument (cold KOH 50% for 14 hours, 700 di- 

 ameters magnification) to show the mesosternal furca (MOF) and 

 metasternal furca ( MEF ) , as well as the whorled tubes of the foveae 

 II and IV. Note relation of mesosternal furca to fovea IV. Fovea III 

 is median and unpaired. All foveae (II, III, IV) and pubescent. 



Fig. 6. Rhexidius canaliculatus (LeConte) and Rhexius insculptus LeConte. 

 In these two trichonychine species fovea II of the mesosternal field 

 is large but typical of Pselaphidae. However, in fovea III on each 

 side the fovea in reality is bifurcated into two foveae with a common 

 orifice. This condition is shown in the figure. Slide mount, 4(!0 di- 

 ameters. 



Fig. 7. Pilopius lacustris Casey. 



Mesosternal and metasternal fields. Legend as in Fig. 1. MOF, meso- 

 sternal furca; MEF, metasternal furca; MOC, mesothoracic coxa; 

 T, mesothoracic trochanter; F, mesothoracic femur; MEC, meta- 

 thoracic coxa. Note that foveae II and III are paired, while fovea VI 

 is median and unpaired. All foveae are nude. Fovea VI is shown with 

 transparent integument to show whorling of fovea. The character- 

 istic scale pubescence (a) is enlarged to show its elongate, thin 

 paddle-shape, the deep puncture in which it is set, and the long tube 

 or air space which runs from its tij) through the base of the bulb of 

 the scale into the integument where it expands into what appears 

 to be a sac. 



Fig. 7a. Foveae II and III of Fig. 7, enlarged at 700 diameters to show whorled 

 walls in the prepectoid area. 



