802 



ARTHROPODA 



PHYLÜM VII 



beeil derived a iiumber of more 



MediaslinaL 



Scapidar 



fjrterriomedicai 



i 



Anal Veins 

 Internomedian 



Froiu this generalised stock liave proLably -^ -, ,. n i Ar 



specialised faniiL, also limited to tlie Paleozoic (Upper Productive Goal Measures 

 A and Permian), among which may 



be mentioned tlie followiiig : 



Spiloblattiiiidae, with smootli 

 fenestrated Spaces between the bor- 

 dered loiigitudiiial veins of the 

 tegmina ; Mylacridae, with the sub- 

 costal branches giveii off from a 

 common point of origin at the base 

 (Fig. 1548, C); Poroblattinidae 

 and Neorthroblattinidae, with a 

 very short siibcosta ; Mesoblatti- 

 nidae, with the subcosta forming 

 only a calloiis at the base of the 

 anterior border ; Pseiidomylacridae, 

 Dictyomylacridae, Neomylacridae, 

 Pteridomylacridae, Idiomylacridae, 

 Diechoblattinidae, and Protere- 

 midae. 



Tertiary cockroaches are all 

 referable to modern families, and 

 are probably descended, at least for 

 the greater part, from the Mesoblattinidae, a family which is abundantly represented 

 in Jurassic rocks. Many larval forms and even ^^^'g packets of cockroaches are foiiiid 



Fig. 1547. 

 Neuration of one of the tegmina of a Paleozoic Cockroach 

 Asemoblatta mazona (Scud.), from the Coal Measures of Illinois. 

 Tlie veins are named at the base of the tegmen, and the areas 

 are marked along the margin. 2/j (after Scudder). 



Fi(i. 1548. 



specialised 



'''''"" 'Äimiyfcrid "''cTiLwf ^ ?''• ^t ^^' ^"'"*"^'' Archimylacrid. B, More highly 

 Arclumlyacrid. L, Mylacns, typifying the Mylacridae. Nervures are marked as in Fig. 15 



fossil. Specific determinations are often difficiüt, no two individii^ls being exactly 

 MvidTd. ''''''"' '''' '""''^"'^ ^'^'''''' ^^'' ''^^^ ^^^ left wings of the same 



