322 MR. HENRY WALTER BATES ON PHASMIDÆ. 
The new species added to the family in the present paper do not contribute any 
king new feature to enlarge the range of grotesqueness and magnitude of form whic 
known to distinguish the Phasmidæ above all other insects. They enable us, how 
by their confirmation or otherwise of the genera that have been proposed, to get a 
insight into the working of Nature in the production of these extraordinary creatum 
and to settle the groundwork of their classification. In the first place, the very 
apparent diversity in the family, with very little real departure from the family 
becomes more marked as our knowledge of the group increases. There are species 
bodies so attenuated that they resemble smooth stems of grass, others of great bulk, arm 
on body and limbs with tegumentary lobes or spines, and others, again, dilated im 
thin leaf-like expansions. Some have extremely short antennæ, and others have the 
members excessively elongated. The head is most diversified in shape—globular, conie 
oval, linear, spined or smooth, furnished with important organs (like simple eyes) or 
stitute of them. Some species are wingless in both sexes, others are winged in the male 
and wingless in the female; many, again, are winged in both sexes, whilst others ha 
rudimentary wings either in one sex only or in both. The abdomen and its appendages, 
and the legs, have also profound modifications of form. It is seldom that these div 
ties of structure help us in classification; species agreeing in some one or two featu 
. that might be generie differ greatly in other features which might equally be consid 
generic. Each species, almost, has well-marked and apparently important stru 
peculiarities, and the definition of generic groups is a matter of extreme dificul 
There is very little difference in habits of life ; all are vegetable feeders, necessar 
sluggish in motion, owing to their elongated and many-segmented forms, and pass th 
lives on trees. This irregular diversity is perhaps only an exaggeration of what is se 
in many other groups of animals and plants, and its explanation may be sought in t 
homogeneity of type of a group with much adaptive modification of its members. Wh 
a group is easy to classify or subdivide, this probably results from real heterogeneity 
type—a heterogeneity which is fundamental, but not sufficiently great to prevent the co 
ponent parts from being included in the group. Now the Phasmidæ appear to consist oi 
a set of forms typically moderately elongate or cylindrical, and winged in both sexes, 
in other families of the order (Orthoptera) to which they belong, but which have become 
benc codd iq a dd ced ern 
6. Bacteria azteca, Sauss. I. c. 
7. Bacteria polteca, Sauss. 1. c. 
8. Bacteria baculus, Sauss. l c. , . 
9. Bacteria (Bacunculus) æstuans, Sauss. Ann. Soc. Ent. Fr 
10. Bacteria cornuta, Sauss. Rev. et Mag. Zool. 1861, p. 128 
11. Bacteria subnematodes, Giebel, Zeitschr. f. d. gesammt. Naturwissensch. 
12. Acanthoderus mexicanus, Saussure, Rev. et Mag. Zool. 1859, p. 62 
13. Acanthoderus (Xylodus) adumbratus, Sauss. l.c. p.62 , . 
14, Cladoxerus rubus, Sauss. Rev, et Mag. Zool. 1861, p. 128 . iod . 
15. cappa e 8.) tiarata, Stal, Ofversigt af Kongl, Vetensk. Akad. Förhandlingar, 
Ep , . e . . " 
16. Achrioptera (n. g.) fallax, Coquerel, Ann. Soc. Ent. Fr. 1861, p. 495, pl. 9. fig. 1 
. 1861, p. 474, pl. 11. fig. 2 
xviii. p. 113 . 
Li B 
17. Prisopus mexicanus, Saussure, Rev. et Mag. Zool. 1859, p. 61 
