[Illustration: FIG. 131.—_Pseudoglomeris fornicata_, ♀. Burma. Tribe Perisphaeriides. (After Brunner.)] Some of the species of _Holocompsa_ remind us strongly of Hemiptera of the family Capsidae; they have an arrangement of colours similar to what prevails in that group, and their tegmina and wings which, as being those of Blattids may be said to be abnormally formed, resemble in texture and the distribution of the venation those of the Hemiptera. These Insects are closely allied to _Diaphana_, of which genus we have figured a species (Fig. 122). {236}There is very little evidence on which to base an estimate of the number of species of Blattidae existing in the world at present. Probably the number extant in collections may amount to 1000 or thereabouts, and the total existing in the world may be as many as 5000. The species of Blattidae cannot tolerate cold, and are consequently only numerous in tropical regions. Europe possesses about twenty species, and in Britain there are only three that are truly native; these are all small Insects belonging to the genus _Ectobia_, and living out of doors, amongst leaves, under bushes, and in various other places. We have, however, several other species that have been introduced by the agency of man, and these all live under cover, where there is artificial warmth and they are protected from the inclemencies of the winter season. The commonest of these forms is _Stilopyga orientalis_, the "black beetle" of our kitchens and bakehouses. This Insect is said to have been brought to Europe from "Asia" about 200 years ago, but the evidence as to its introduction, and as to the country of which it is really a native, is very slight. It is indeed said[163] that _S. orientalis_ has been found in peat in Schleswig-Holstein. _Periplaneta americana_ is a larger Insect, and is common in some places; it is apparently the species that is most usually found on board ships, where it sometimes multiplies enormously, and entirely devours stores of farinaceous food to which it obtains access: it is known that sometimes a box or barrel supposed to contain biscuits, on being opened is found to have its edible contents entirely replaced by a mass of living cockroaches. Fortunately _Periplaneta americana_ has not spread widely in this country, though it is found in great numbers in limited localities; one of the best known of which is the Zoological Gardens in the Regent's Park at London. _Periplaneta australasiae_ is very similar to _P. americana_, but has a yellow mark on the shoulder of each tegmen. This has obtained a footing in some of the glass-houses in the Botanic Gardens at Cambridge and Kew; and it is said to be fairly well established in Belfast. Another of our introduced domestic cockroaches is _Phyllodromia germanica_, a much smaller Insect than the others we have mentioned. It has only established itself at a few places in this country, but it is extremely abundant in some parts of Northern and Eastern Europe.