ORTHOPTEEA OF INDIANA. 173 



Yvoni the other Orthoptera (except the Mantidce) the Blattidce 

 differ widely in the maimer of oviposition, as the eggs are not laid 

 one at a time, but all at once in a peculiar' capsule or egg case called 

 an oothec'a. These capsules vary in the different species as regards 

 the size, shape, and the number of eggs they contain, but they are all 

 similar in structure. Each one is divided lengthwise by a mem- 

 branous partition into two cells. Within each of these cells is a sin- 

 gle row of cylindrical pouches, somewhat similar in appearance to 

 those of a cartridge belt, and within each pouch is an egg. 



Fig. 22. Ooih^dA oi Blaita or itntalis; a, side; 6, end view. Natural size indicated by out- 

 line figure. From "Household Insects", published by U. S. Div. of Entomology. 



The female cockroach often runs about for several days with an 

 ootheca protruding from the abdomen, but finally drops it in a suit- 

 able place and from it the young, in time, emerge. While this 

 method of oviposition is the one practiced by all the species of com- 

 mon occurrence in the United States, there seem to be exceptions to 

 it, as Dr. C. V. Eiley has recorded the fact of an introduced tropical 

 species, Pancklora poeyi Sauss., being viviparous, the young emerging 

 alive from the body of the parent, and a careful dissection of the 

 latter showing no trace of either eggs or ootheca. 



All young cockroaches resemble the parents in form but are wholly 

 wingless, the wings not appearing until after the fifth or last moult. 

 The young are often mistaken for the mature by persons who have 

 not made a careful study of the life history of the insects; and those 

 of one or two well-known and common forms have, in the past, even 

 been described or figured as distinct wingless species by some of the 

 leading entomologists of the country. 



To the paleontologist, interested in tracing back the ancestry of 

 insects, the Blattidce become at once a group of surpassing interest, 

 for some of the oldest known insects are cockroaches from the Silu- 

 rian and Carboniferous rocks. Between 130 and 140 fossil species 

 of the family are known from the Paleozoic rocks of the United 

 States, principally from the Carboniferous formations, but some from 

 all the ages as far back as the middle Silurian. Mr. S. H. Scudder, 

 of Cambridge, Mass., the most eminent authority on insect paleon- 

 tology, says of the c'ockroach: "Of no other type of insect can it be 



