17G THE CANADIAN ENTOMOLOGIST 



without ventral seta>. Clothing merely a row of short, blunt simple setae across 

 middle of each segment with a few minute setae in addition (Fig. 8) Maximum 

 length 1.5 mm. Found August to October trapped on water in little cups 

 eroded in limestone on shores of Ottawa Ri\'er at Marshall's Bay, near Arnprior, 

 Ontario. 



The most dislinctixe feature of this species is the long, elliptical, postantennal 

 organ of numerous elements. While these elements are usually referred to as 

 tubercles, in this instance when viewed in plan they look like flat, overlapping 

 plates; in f.erspccti\'e they are seen to l)e somewhat inflated, outstanding, o\-al 

 leaves. 



The two rows ol light spots (low n ihe back ma\' also serve lor a preliminary 

 idrnlihcation, and ])ossibl\' tln'se ma\' prox'e to be a constant iharac'teristic; 

 but c(il(iralion is so unstable with main' ( 'olicmbolans that little weight should 

 be gi\en to their presence or absence. 



It is a i^leasure to acknowledge the generous help that Dr. J. \V. I'Olsom, 

 of the Uni\ersit>' of Illinois, has given me in separating this species. Mis 

 criticisms and suggestions have been of the gre^itest assistance, and I am in- 

 debted to him for pointing out some of the morphological niceties that the 

 average microscopisl cannot see until he is told where to look for them. 



l^XIM.AN.VnON ()!• Pl..\TE V. 



Fig. I. Pscnihu lioi'iiles saxalilis x-lf). 



2. Fyes and postantennal organ of left side. x8r)0. 

 ;i. Postantennal organ. x780. 



4. Olfactory seta^ of right antenna', dorsal aspect. (LIndillerentiate<l 

 setaj are omitted). x450. 



5. Sense organ of third antennal segment. xlijOO. 

 0. Right hind foot. x730. 



7. Right mucro ;uul part of dens. \(1(»(). 

 S. I'irst al)d()iniiial segment. xHOO. 



A NEW MVZOCALUS (APHIDID^: HOMOPTRRA). 



P.Y W. M. D.WIDSON, 

 I'. S. HiiiT'au (if Knloniol()!.i\-, Alhanihra, ("alii".*. 



Myzocallis alhambra, sp. nov. 



Bod\' non-luberculate; wings clouded; cornicles and tibial bases ])ale.. 

 Alate \i\iparous lemale. 



Oeneral colour pale lemon \'ellow, suffused with ])ink antl light orange. 

 Shape of body rather narrow. Antenna^ slender (thir.d joint slightly enlarged 

 on liasal half), about as long as the body, ]:)ale yellow, articulations narrowly 

 dusky brown; joint III bears from 2 to 4 circular sensoria on basal half; filament 

 of distal joint longer than base; relati\'e lengths of joints: III WM , W 2X\, \ 

 250, \'I 183 + 18(J; joint I\' is sometimes longer than joint V, and vice versa. 

 Head and thorax somewhat dusky on sides; forehead produced obtusely in 

 centre, its longest hairs about one-fourth as long as the head is wide between 

 the anteniKc, ol)scurely cai)ilate; beak jiale >'ellow, tip black, reaching barely to 



August, I'.ii-'ii, 



