184 Psyche [December 



still living, but these genera were supposed by him to be later than 

 Palaeozoic. On the other hand, Handlirsch, if we except genera 

 unknown to Scudder, places only the cockroaches in a modern 

 order. The main issue therefore narrows down to (1) Whether 

 the Palaeozoic cockroaches in general, or only some of them, should 

 be placed in the same order as the living ones, and (2) whether 

 among the Palaeozoic insects excluded from modern orders, we 

 should recognize one order or many. Even so, the disagreement 

 diminishes when we note that Scudder opposed his Palaeodictyop- 

 tera to a group of equal rank including all other insects, and 

 divided it up into sections which he considered related to the 

 modern Neuroptera, Orthoptera and Hemiptera. To a consid- 

 erable extent the apparent difference is due to different conceptions 

 of what constitutes an order; thus Handlirsch makes several 

 orders out of the living Orthoptera, usually considered to be one. 

 In detail, there is more serious disagreement as to the placing of 

 various genera, and since many of these are known from very 

 unsatisfactory fragments, it is likely that diverse opinions will 

 prevail in the future as in the past. If many writers, for reasons 

 of convenience, adopt throughout the nomenclature of Hand- 

 lirsch's great work, this will not necessarily imply critical judgment 

 between opposing opinions. In this comparison, the data from 

 Scudder are taken from his summary published in 1886, with 

 some additions from later works. 



Since Handlirsch published his classification, Sellards has made 

 known a magnificent series of insects from the Permian of Kansas. 

 In connection with a very large and well-preserved dragon-fly, he 

 discusses the standing of the Protodonata, and arrives at the 

 conclusion that they should rank as a sub-order only, under 

 Odonata. Sellards also reports from these deposits a series of 

 ten genera and thirteen species of Plectoptera (Ephemerids), 

 forming a new family Protereismatidse (Protereismephemeridae, 

 Sellards). Summing up, we may consider the following propo- 

 sitions valid, so far as present knowledge goes: 



(1.) During the later Palaeozoic the Blattoid Orthoptera were 

 well established, and in the latest Palaeozoic (Permian) the Ephe- 

 merids, and possibly the Perlids and Mantids, had become suffi- 

 ciently differentiated to be placed in the same orders as their 

 living representatives. 



