204 NOETH AMERICAN SCELIPHRON (hYMENOPTERA) 



rubbed off in older specimens. In other words the punctures 

 mark the places of attachment of the hairs to the chitinous 

 integument of the insect's body. 



Some of these punctures are so small as to be visible only under 

 a high powered lens and the corresponding hairs are very fine 

 and usually decumbent. Such hairs may be seen on the dorsal 

 segments of the abdomen and the terms "fine sericeous" or 

 "sparsely sericeous" are applied to such areas. Similar minute 

 but somewhat denser hairs are found on the legs and are called 

 "sericeous" or "densely sericeous." These last are dark or 

 whitish according to the species, while the "coarse sericeous" 

 hairs found on portions of the fore and hind tibiae are always 

 dark. 



There are two regions in which the hairs are seen to lie flat 

 down on the integument and are so closely set as to hide the 

 ground color of the body, and give it a soft, satiny appearance 

 when viewed from certain angles. The hairs in these regions are 

 called "pubescent." One region is found along the sides of the 

 clypeus and the frons where the hairs are silvery, and more 

 developed in males than in females. The other region consists of 

 two somewhat circular areas on the third and fourth ventral 

 segments of the abdomen of Sceliphron cyaneum females, and the 

 hairs in this instance vary from dark to pale brown when seen 

 from different angles. 



From the above description it may be noticed that the terms 

 "sericeous" and "pubescent" apply to fine decumbent or semi- 

 decumbent hairs and the chief point of distinction seems to be in 

 their density and length, since the sericeous hairs are shorter and 

 only partly disguise the color of the integument, while the longer 

 pubescence may completely hide the underljdng chitin. 



The remaining portion of the vestiture of the body in these 

 insects is composed of erect or nearly erect, more or less coarse 

 hairs, which are attached to distinct punctures of varying sizes 

 and density of arrangement. In connection with this part of 

 the vestiture the writer has used the terms "hairs" or "erect 

 hairs, " coupling with them various words to denote gradations in 

 density and coarseness. The coarsest hairs are found on the 

 clypeus, the genae, the "end" and "sides" of the propodeum, 



