12 HEMIPTERA-HETEROPTERA. 
8. Thyreocoris quadrisignatus. (Tab. II. fig. 17.) 
Thyreocoris quadrisignatus, Stall, Stett. ent. Zeit. xxiii. p. 94. 441; En. Hem. v. p. 24. 16. 
Hab. Mexico!; British Honpuras, Rio Hondo (Blancaneaua). 
9. Thyreocoris incertus. (Tab. III. fig. 4.) 
Corimelena incerta, Uhler, Proc. Ent. Soc. Phil. ii. p. 156. 3'. 
Hab. NicaRnagua.—CvusBal, 
The specimen figured is from Nicaragua, for which I am indebted to the kindness of 
Prof. Uhler. 
CYRTASPIS. 
Cyrtaspis, Stal, Rio H. i. p. 9 (1860) ; En. Hem. v. p. 25 (1876). 
Megaris, Stal, Rio H. ii. p. 57 (1862). 
The orbicular and hemispherical body, with the small head carried almost in the 
same perpendicular plane with the anteriorly sharply truncated pronotum, are alone 
characters sufficient to distinguish this genus from any other of the Cydnine here 
enumerated. | 
1. Cyrtaspis atratula. (Tab. IV. fig. 13.) 
Megaris atratula, Stal, Stett. ent. Zeit. xxiii. p. 84. 16}. 
Cyrtaspis atratula, Stal, En. Hem. v. p. 25. 
Hab. Mexico (Mus. Berol.), Tabasco}. 
Subfam. SCUTELLERINE. 
The Scutellerine of Central America, roughly calculated, are in genera about two 
fifths and in species rather higher, in comparison with the number of genera and 
species respectively of the whole Nearctic and Neotropical Regions. With few exceptions 
these two regions approximate to the Palearctic in the paucity of the number of species 
found in them, the smallness of their size, and the obscurity of their colour as compared 
with those of the Ethiopian, Oriental, and Australian Regions. If to these last three 
we add the Palearctic and compare the number of genera and species with those of 
the Nearctic and Neotropical Regions,. the last are found to contain only about two 
thirds the number of the former in genera, and less than half in species. 
‘The great amount of colour-variation, and even of size, to be observed in the species 
of this subfamily has added much to the difficulty of proper specific identification, 
and therefore necessarily increased the synonymic nomenclature. But the more 
interesting and much more difficult problem is to find the biological explanation of so 
many representatives of different genera all varying in one peculiar and uniform direc- 
tion. Thus in the genera Homemus, Sphyrocoris, and Symphylus there are species always 
