256 Mr. S. H. Sciidder on Triassic Insects 



Fossil Insects of the Secondary Rocks of En,ffland ' 

 (London, 1 845) , and bj Dr. Eugen Geinitz, in his recent 

 paper on the Dobbertin insects *, in which one species is 

 figured from the lower Jura ; but the great mass of Jurassic 

 species are plainly more closely related to living forms, and 

 neither in the independent existence of the veins which are 

 characteristically distinct in Palosozoic types, nor in the 

 course of the anal nervules, do they show any affinity to the 

 Palajoblattarite. 



Eleven of the seventeen species of cockroaches, and five of 

 the nine genera found at Fairplay belong to the Palreo- 

 blattariffi. These five genera are the following : — Etoblat- 

 tina (1 species), Petrahlattina (2 species), Aiithracohlatfina, 

 very doubtful, the specimen being very imperfect (1 species), 

 Spilohlaitina, nov. ^^n. (4 species), and Poroblatlina^ nov. 

 gen. (3 species). Only four of the eleven species therefore 

 belong to known genera, and one of these is doubtful ; but 

 the difi"ercnce is more marked than this, for the species 

 referred to Etohlattina is an aberrant form with an excessively 

 long internomedian vein, and both the species of Ptf?ra6/a^M«a 

 agree in differing from those heretofore known to a very 

 considerable degree. Of the wqw genera Spilohlattina is 

 very peculiar in the strongly divergent and then convergent 

 curve of the externomedian and internomedian veins aiound 

 a large stigma near the middle of the wing, unknown in any 

 other cockroach, ancient or modern, so far as I know ; but 

 otherwise it is related to Etohlattina^ while Porohlattina is 

 more nearly related to Petrahlattina^ and especially to the two 

 new species of that genus from this locality. 



The average size of these I'airplay Pala3oblattaria3 is much 

 less than that of the Paleozoic Pala^oblattariaj in general. 

 The average length of the front wings of the Palaeozoic 

 species is 26 millim. ; that of these Fairplay PalteoblattariEe 

 16 millim. This fact has its value, for the Jurassic species 

 are nearly all of very small size, and the wing-length of the 

 remaining species from Fairplay {i. e. those which do not 

 belong to the Palajoblattarire) is less than 8*5, ranging from 

 6*5 to 11"5 millim. This agrees completely with the size of 

 IVIesozoic species already known. The average of all the 

 Fairplay cockroaches is less than 13'5 millim. 



As to the six cockroaches from Fairplay which do not 

 belong to the Palffioblattarige, the characteristics of their 

 venation as well as their small size show them to be closely 

 allied to Jurassic forms, although the three or four genera to 



• Zeitschr. deutscli. geol. Gesellscli, 1880, p. 610. 



