DIESTOSTEMMA. | 207 
Fam, TETTIGONIIDA. 
The members of this family are characterized by having the ocelli, which are usually 
very conspicuous, on the disc of the vertex of the head, so that they look directly 
upwards and are at right angles to the perpendicular axis of the eyes; the latter are 
usually promiment; the general form is elongate, sometimes considerably narrowed 
behind, but usually parallel; and the hind tibie are multispinose. 
The Tettigoniidze include a very large number of species, the genus Tettigonia, as 
limited in this work, being cosmopolitan ; the characters, however, of the genera which 
have hitherto been formed are most unreliable, owing to the occurrence of such a large 
number of intermediate forms. Amyot and Serville tried to divide the family, but 
apparently they had hardly any material to work upon, and Walker, while adopting 
their genera, seems to have had very little idea of their limits or characteristics: this 
is, perhaps, not to be wondered at, as nothing can be more meagre than Amyot 
and Serville’s descriptions. Signoret, at the beginning of his Monograph [ Ann. Soc. 
Ent. Fr. sér. 3, i., ii., iii, (1853-1855) |, which still remains the most important work 
on the group, simply ignores all the genera and places the whole of the species under 
Tettigonia ; he gives his reasons in full (doc. cit. i. pp. 16-18), and everyone who 
works at the group must agree with what he says as to the impossibility of making 
any satisfactory division owing to the fact that the characters always overlap in some of 
the species. Stal (Kongl. Svensk. Vet.-Ak. Handl. Band viii. No. 1) is the only writer 
who has made a serious attempt to tabulate the family, and I have thought it best, to a 
certain extent, to follow him, more for convenience’ sake than because he has in any way 
settled the question, for the very large genus Tettigonia, containing by far the greater 
part of the species belonging to the family, will remain practically untouched. Although 
Signoret does not adopt genera, yet he throws the inclusive genus Tettigonia into groups 
and series which are very uneven and more confusing than Stal’s genera. 
I have not followed St&l in giving a dichotomous table of the group, as it appears 
to me impossible to draw up one that is of any practical use: the characters are 
transitional and it is only by taking a number of them together that any division at all 
can be made. 
DIESTOSTEMMA. 
Diestostemma, Amyot et Serville, Hist. Nat. des Ins. Hémipt. p. 572 (1843). 
The members of this genus appear to be widely distributed in Central and South 
America; they are conspicuous insects, resembling white moths. The head is very 
considerably produced in a blunt triangle, and the ocelli are much nearer to the eyes 
than is usual in the Tettigoniide ; it is furnished in front, in one species at least, with 
a long snout-like appendage, which fits on to a small peduncle—the use of this is not 
apparent as it is very easily shed, one specimen only in our collection possessing it. 
