PLATE XXXII. 



Fig. 1. Amhrysus melanoptervs Stal. The genital segment from a specimen in the 

 Snow collection determined by Van Duzee. The segment is more elongate than A.. 

 signoreti and the claspers more slender and truncate at tip. Another character in this 

 group that may have possibilities is a chitinized flap that is present on the margin of one 

 of latter abdominal tergites. Its position is on the right side in the material of the two 

 species examined and distinctly different in shape. 



Fig. 2. Saldid. The exposed genital segment of a species common in Kansas. Note 

 the shape of the claspers and the tip of the genital segment as compared with Pentacora 

 signoreti Giier., fig. 6. 



Fig. 3. Amhrysus signoreti Stal. The genital segment from a specimen in the Snow 

 collection determined by Van Duzee. The segment is plump and the claspers broad. The 

 drawing is partly free hand and from dorsal view. This bug was taken by Doctor 

 Snow at San Barnardino Ranch, Arizona (Cochise county). 



Fig. 4. Notonecta mexicana. The male genital capsule of this species is much larger 

 in proportion to the size of the insect than any other member of the genus examined. It 

 differs from the others in having the cephalic end larger than the caudal end and in 

 having a greatly developed lobe before the clasper. The drawing is to about the same 

 scale as those on plate 1, and the insect about the size of N. insulata and N. irrorata, the 

 genitalia of which are shown on figures 9 and 7 of plate XXXI. 



Fig. 5. Oelastocoris variegatus (Guer.). The specimen from which this drawing 

 was made bears Uhler's determination and was loaned for study by Mr. E. H. Gibson, 

 custodian of the Hemiptera in the National Museum at Washington. The drawing is 

 made from a ventral view of the bulb. In this genus the genital segment is asymmetrical, 

 the right clasper (R. C.) being much more developed than the left (L. C.) and armed 

 with short peg-like processes. The segment has revolved a quarter turn to the right so 

 that the tips of the claspers are directed to the right instead of dorsally. The general 

 features of the genital ai-mature are the same for all, but the western and eastern forms 

 fall into two distinct groups as regards the shape of the right clasper. The right clasper 

 (R. C, see figure) is produced on its caudal margin into a flat plate which bears a 

 curved more or less finger-like process. The distal angle (a) which this plate forms with 

 the shaft of the clasper is acute in all the western material and obtuse and sloping in all 

 the eastern material examined. In Kansas we have both forms. A series from western 

 Kansas (Pawnee county) compare closely with this Uhler specimen. As a whole, they are 

 pebbled and colored like the sand of the river flats upon which they live. A few speci- 

 mens are more obscurely marked. There is no perceptible difference in the male genitalia 

 of the whole series, however. In the Snow collections under G. oculatus there are speci- 

 mens from Bill Wins Ford, Arizona, taken by Doctor Snow. Some are distinctly mottled 

 and others more obscurely marked. The crenations and angles of pronotal margins are 

 as in the G. variegatus (Guer.), determined by Uhler. The right clasper is acute angled, 

 also. They are certainly the same as Uhler's G. variegatus (Guer.). 



Fig. 6. Pentacora signoreti. The genital segment of a species common in the western 

 portion of Kansas. Determined material by Van Duzee. The two species are here shown 

 to suggest that a study of these parts should be made in making a study of the family. 

 They may have some taxonomic value. 



Fig. 7. Gelastocoris oculatus (Fabr.). The specimens of the material from eastern 

 Kansas, Tennessee, etc., as a whole, are less variegated in color pattern and from Mr. 

 J. R. de la Torre Bueno's notes (in litt.) are probably G. oculatus (Fabr.). These all 

 agree in having the obtuse and sloping angled right clasper. Kansas is splendidly sit- 

 uated for a study of geographical convergence. Western forms and eastern forms meet 

 and Upper Austral and Lower Austral life zones are present. Dr. C. H. Kennedy's study 

 of the dragon flies has directed attention to this interesting feature. One of our graduate 

 students is now engaged in working over the distribution of the toad bugs with this 

 point in mind. A study of a wide range of material of each form will always be essential 

 to the establishment of the range of variation in the species, and any character which is 

 specifically discontinuous and unique to a species is always a welcome, discovery. 



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