THE CANADIAN ENT()MOL< KWKT. 237 



NOTES ON PACHYBRACHYS AND DESCRIPTIONS OF NEW 



SPECIES. 



BY FRED. C. BOWDITCH, BROOKLINE, MASS. 



In what is regarded as the most typical Pachybrachys, the thorax has 

 a well-defined M-like mark ; it varies with different species from an almost 

 complete M through various partial marks and clouds until, in some cases, 

 it is hardly visible ; but of the thoracic markings, most are variations of 

 this M, and for brevity in description it is called the M ; this is often 

 supplemented by a transverse impression in the rear, terminating on each 

 side in a small shaded depressed area, the depression forming the ends of 

 the M arms ; almost invariably the darker portions of the head and thorax 

 are the most densely punctured. 



In the species showing striate, punctate elytra, the best developed 

 (pallidipennis, Suff.) shows ten regular striae and a marginal stria, but, 

 in nearly all our species, these stri?e are more or less broken ; of the costse 

 or intervals, the third, fifth and humeral are the most enduring, and in 

 most species some, or all, of these spaces are more or less indicated; the 

 third is the most important of the three, and reaches its highest develop- 

 ment in forms like balsas, nov. sp. The striae on either side are perfect, 

 and form a regular space from base to apex, the inner or third stria is 

 dilated in the middle towards the suture, and forms the elytral or sutural 

 shield, a smooth area about the middle of the elytra, and in many species 

 a marked feature, varying from a regular circle (inclusus, Jac), or triangu- 

 lar spot ( labyrinthitis, Suff), to nothing. The punctured scutellar area 

 includes everything between the base, the third interval and the elytral 

 shield or a trifle beyond. In counting the striae, I call the sutural the first. 



Where the elytra have dark spots or marks, the typical or standard 

 form seems to be three spots on, or near, the margin, one at, or near, the 

 humerus, one about the middle, and the last about the convexity, and 

 three more spots on the inside, parallel to the suture ; the first is on, or 

 about, the third interval, a little back of the forward edge, the second 

 behind it in the middle, and the third further back on the convexity. All 

 ihe spots are parallel to each other and the elytral suture. These marks 

 may be spread out so as to join either longitudinally or sideways or be 

 partially or wholly absent ; this spotting or some variation is used in many 

 of the species, and may, for convenience in description, be called the 

 standard form of spots. The most enduring of the spots is the humeral, 

 and when only symptoms of the others appear the humerus will usually be 

 dark. The marginal stria varies greatly in sinuation behind the curve of 



July, 1909 



