12 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.65. 



setae " and those added in the second and third instars as " secoridary 

 setaey To facilitate referring to them the primary setae on the pro- 

 notum have been numbered. Their position and nomenchiture is 

 shown in figures 49 to 57. On the abdomen primary and secondary 

 setae appear to be present, but their homology was not determined 

 sufficiently to give them numbers. Their number and position is 

 indicated in figures 88 to 93. 



In the genera Tetracha and Omus limited studies indicate the 

 presence of primary and secondary setae. There Avas not a sufficient 

 amount of material available, however, to make it possible to indi- 

 cate these by numbers. The setae on the pronotum of the first, second, 

 and third instars and on the third abdominal segment of the first 

 and third instars of Omus calif ornicus are shown in figures 82 to 

 84 and 118 and 119. 



No immature larvae of the genus AmhlychUa were available for 

 study. 



DISCUSSION OF THE CHARACTERS USED IN CLASSIFICATION. 



All measurements have been made with a binocular microscope 

 and an eye-piece micrometer. One of the best uses which can be 

 made of measurements, as has been determined by a number of work- 

 ers on various species of insects, is the proportional length of one 

 structure to another. This proportion is constant for individuals of 

 different sizes of the same species, and often for the different instars. 

 The proportional length to the width of the frons, the proportional 

 diameter of ocellus 2 to the distance between ocelli 1 and 2, the pro- 

 portional length of the segments of the antennae, and the length 

 and width of the pronotum are good characters. In general, 

 ocelli 1 and 2, the homology of which is indicated in figures 5 and 8, 

 are very much the same size in the large and small species of the 

 genus Cincindela, but they appear to be larger in the smaller species 

 due to the smaller size of the head. As a result, in the smaller 

 species, the distance between ocelli 1 and 2 is generally less than the 

 diameter of ocellus 2. 



The proportional length of the segments of the maxillary palpus 

 furnish excellent generic characters but do not vary enough within 

 the genera to be of specific value. The position of the cephalo-lateral 

 angles of the pronotum with respect to the cephalo-mesal part and 

 the general shape of the pronotum varies considerably in the species 

 of the genus Cicindela. 



The setae on the dorsal aspect of the head and pronotum, and on 

 the abdomen provide further characters for separating the species. 

 In the genus Cicindela the setae on the U-shaped ridge on the caudal 

 part of the frons are very constant in number for those species which 

 have only two. These are usually large and easil}^ distinguished. In 



