INTRODUCTION. 1X 
The Notonectide, or ‘‘water-boatmen,” are represented within our limits by three 
genera only, Motonecta, Anisops, and Plea, the first two by the same number of 
species. Of the eleven forms noticed, four of the Anisops are treated as new. 
The Corixide are so poorly represented in our collections that very little can be said 
‘about them. Various Corize recorded from within our limits are unknown to me, 
and of several of the other species of that genus but few specimens are available for 
examination. Nevertheless, one of them, C. mercenaria, abounds to an incredible 
extent in the lagoons of the central plateau of Mexico, and this shows that we can 
have no idea at present of the actual number of Central-American forms. Thirteen 
species of Corixa, six of which are treated as new, and one of Tenagobia, are enumerated, 
but it is almost certain that some of the former will prove to be synonymous when 
the types can be compared. 
The number of species for the nineteen families is 592, with 289 new and 
thirty new genera. For the first twelve of these families Lethierry and Severin (1896) 
give 3144* species for the whole world, as against our 517. In Vol. L., for the 
families Pentatomide, Coreide, Lygzide, Pyrrhocoride, and Capside, 1108 species 
are enumerated, with 581 new. The total number of Heteroptera recorded in this 
work (including the fifteen additions to Vol. I., noticed on p. 384) is therefore 1715, 
rather more than half of which have been treated as new. 
We are again much indebted to the authorities of the Stockholm, Vienna, and 
Berlin Museums, as well as to Dr. E. Bergroth and Mons. A. L. Montandon, for the 
loan of various types or co-types, many of which are figured on our Plates. Of these 
latter, twenty-two have been required, six of which are coloured, the whole of them 
having been carefully drawn by Mr. E. Wilson of Cambridge. 
Mr. Distant, in his Introduction to Vol. I., has already noted the sources from 
whence our collections have been derived, and his remarks apply equally well to the 
insects dealt with in the present volume. 
G.C.C. 
June 1901. 
* These figures, however, are much too high in reality (many of Walker’s so-called species being 
counted), notwithstanding that there is a mistake in adding up, the actual number being 3186. 
BIOL. CENTR.-AMER., Rhynch., Vol. IL., June 1901. b 
