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SPHENOPHOEUS. 



153 



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This cosmopolitan genus, as at present restricted, may be said to have its head- 

 quarters in the United States, to judge from the numerous forms added during recent 

 years; and a considerable number are also found in Mexico, one only of these latter 

 (S. incurrens) being known as yet to extend southward through Central America. 

 In Tropical South America and the Antilles, Splienophorus seems to be replaced to a 

 certain extent by Merothricus, Chevr. (type, S. rusticus, Gyll.), the species of which 

 have a rather longer, subconical antennal club. Three of the Mexican forms here 



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* w w *.-» w *. .*. w .».-* l_ 



{-J 



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referred to the present genus (S. aterrimus, S. mundus, and S. octocostatus) have a 

 broad spongy-pubescent third tarsal joint, but they are so obviously related to 

 S. aeqiialis, Gyll., that they must be placed near that insect. Most of them are very 



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variable, as regards the sculpture and incrustation of the surface, there being opaque 

 and shining forms of some of the species, and in consequence they are often difficult to 

 define ; good characters, however, are often to be found in the males. 



Prof. F. H. Chittenden has very kindly presented us with named examples of fifty 

 N. -American species (including many of his own co-types), for comparison with the 

 Mexican forms, the types of nearly all of which I have seen ; but even with this 

 abundance of named material I am unable to arrive at a positive. conclusion as regards 

 the true limits of such species as S. reticulaticollis, S. sulcifrons, and others. Horn's 

 Section B of his Group V. (including insects with the anterior tibise toothed or 

 angulate at the middle) is not represented in our region, and his Group II. has 

 already been dealt with under Cactophagus and Bhodobwnus. 



Many of these insects are destructive to the roots of maize, both in the 



larval and adult stages (S. zece, S. maidis, &c), or attack Pontederia cordata * 

 ( S. pontederia?), Cyperus escitlentus * (8. destructor), grasses, like Distichlidis spicata 



(S. distichlidis), &c. 



The subjoined Table will assist in the identification of the forms enumerated in the 



following pages : 



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; 

 v 



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, 



: 



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a. Third joint of each tarsus large, broad, and spongy-pubescent (except 



along a very narrow median line) beneath, in both sexes ; rostrum 



* 



subcylindrical. 

 a 1 . Upper surface bare and opaque, the prothorax at most feebly punc- 



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tate, the elytral interstices flat. 

 a 2 . Elytral strise obsoletely punctate . 



b 2 . Elytral striae conspicuously punctate 



aterrimus, sp. n. 

 mundus, sp. n. 





b\ Upper surface uneven, the punctures and depressions filled with a 



dense incrustation ; prothorax very coarsely unequally punctate 

 and with a smooth, broad median ridge ; elytra each with four 

 broad costas, the suture also raised and bare octocostatus, sp. n. 



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L 



4 



* A plant found throughout our region (c/. Biol. Centr.-Amer., Botany, iii. pp. 383, 446). 



XX2 







