6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 97 



described by Burgess as effecting the coiling of the proboscis, a find- 

 ing verified by Berlese and later writers. 



The cardo in functional maxillae is usually a small flat sclerite just 

 anterior to the labial palpi. The stipes varies in shape throughout the 



Fig. 2. — Pressure-producing mechanisms of the maxillae. 



A, base of right maxilla of a swallowtail butterfly, ventral view (morpho- 

 logically posterior), showing at Ai a cross-section through the line ab, giving 

 appearance of stipes when proboscis is coiled. B, cross-section of stipes of 

 Catocala sp., showing appearance of pressure chamber {PC) formed by stipes. 

 C, same of Arcyonis alope. D, same of Hcmaris tliysbc. E, same of Danaus 

 menippe. F, same of Pieris rapac. G, base of proboscis of Danaus menippe, 

 lateral view, showing insertion of posterior tentorial proboscis extensor (ptp). 

 H, cross-section of stipes of Hemaris thysbe near insertion of posterior tentorial 

 proboscis extensor (ptp). I, cross-section of stipes of Atrytone zabulon, showing 

 appearance of pressure chamber. 



families above the Tineidae, but when functional always presents 

 fundamentally the same structures. The proximal portion in cross- 

 section always has a median flat sclerite continuous with a tubular 

 lateral part (fig. 2). This tubular part fits into the recurved ventral 

 and anterior ends of the parietal, the lateral edge of the stipes being 



