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180 COLLEGE ENTOMOLOGY
certain species and consist of two pairs which are rather fragile, dusky, membranous,
and similar in size and shape. The venation is poorly developed,
there being only a few longitudinal and cross veins which are slightly more
pronounced in the fore pair. Hairs and transparent longitudinal lines between
the veins and dusky areas are rather prominent features of these alar organs.
Because of the nature of the wings the males must be feeble and erratic fliers.
The abdomen is composed of 10 well-defined segments with evidence of an
11th segment.. The cerci are usually two-segmented, but in the males of the
genus Anisembia Krauss and JUetoligotoma Davis one cercus, always the left
member, is only one-segmented. There are two pairs of thoracic and eight
pairs of abdominal spiracles.
Reproduction is sexual, but certain species are parthenogenetic. There may
be one or many generations a year.
The internal organization is but poorly known. The alimentary canal is
almost straight and consists of the mouth, buccal cavity, narrow pharynx,
dilated o;sophagus and crop, mid-intestine, and slightly coiled hind intestine
with six rectal pupillre. The salivary glands are well developed and the Malpighian
tubules vary from about 20 to 24. There are three thoracic and seven
abdominal ganglia.
The palreontological record of the embiids is imperfectly known, owing no
doubt to their fragility. The first members appear in the Tertiary Baltic
Amber 1 and in the shales of the Lower Permian of Kansas,2 Florissant, Colo.,
and in the Posttertiary of Africa and Asia. According to Tillyard (1926) some
of these forms belong to a new order PROTEMBIARIA which may be an
offshoot of the PROTORTHOPTERA.
This order of insects is now undergoing complete revision by C. Davis and
Edward S. Ross, and it is impossible at this writing to include a satisfactory
system of classification. According to Ross, who has kindly furnished most of
the information as well as the splendid figures used in this chapter, the representatives
are to be arranged in eight families, about 35 genera, and at least
135 species. The three families occurring in North America are ANISEM­
BIIDlE Ross, OLIGEMBIIDlE Davis, and the introduced OLIGOTOMI­
DfE Enderlein. The important world genera are Anisembia Krauss, seven
species, North America; Clothoda Enderlein, five species, South America;
Dihybocercus Enderlein, three species, Africa; Embia Latreille, 18 species,
North Africa; Embolyntha Davis, five species, tropical America; Haplrembt"a
Verhreff, four species, Mediterranean region; Metoligotoma Davis, 21 species,
Australia; Oligembia Davis, seven species, tropical America; Oligotoma Westwood,
23 species, Asia and Australia, and certain species now widely distributed
by commerce; Pararhagodochir Davis, five species, South America;
and Rhagodochir Enderlein, three species, Africa.
What appears to be one of the most widely distributed species is the date
embiid, Oligotoma nigra Hagen, of the Mediterranean region which has been
1 Oligotoma antiqzw Pictet. = HaplUimbia antiqua (Pictet) (Davis, 1940).
• Clothoda spp.?