1864.] 203 



developed, which in many Orthoptera saltatoria is at a very early period. 

 The rule, however, seems to be, that in the larva state an insect moults 

 about four times, and after assuming the pupa state not at all, until its 

 final moult into the subimago or imago state. And this is shown clearly 

 in those Orders (Coleoptera, the true Neuroptera, Hymenoptera, Lepi- 

 doptera and Diptera) which have a quiescent pupa, 'and where conse- 

 quently the line of demarcation between the larva and pupa states is 

 clearly drawn. Consequently, if this be a correct view of the case, 

 just as in Perlina, Ephemerina, Odonata, &c., both the mature larva 

 and the pupa have distinct external rudimental wings, so in the genus 

 Bsetisca neither the mature larva nor the pupa has them. And if the 

 above considerations are correct, in none of these instances can the 

 mature larva be distinguished from the pupa, except by ascertaining 

 whether it has undergone its final moult before assuming the subimago 

 or imago states. As regards Bsetisca obesa, none of my specimens 

 moulted while in my possession, and therefore those from which I bred 

 the subimago must have been pupae when I obtained them. The others, 

 some of which were much smaller and might have been larvae, after I 

 had kept them in water alive for six or seven days, were either dis- 

 .sected or placed in alcohol, without awaiting their further development. 

 If any additional proof was required to establish the validity of my 

 genus Bsetisca, which is itself suSiciently remarkable in its characters, 

 all drawn from the imago, the discovery of the very anomalous cha- 

 racters of its pupa would amply supply the deficiency. 



Genus B^TISCA— Pupa. 

 Head freely moveable and connected with the thorax by membrane, 

 with two horizontally porrect horns springing from above the anterior 

 edge of the front, which are sometimes simply elongate-triangular, 

 sometimes both of them deeply emarginate on the interior edge so as 

 to present the appearance of a long exterior and a short interior horn, 

 .sometimes only one of them thus emarginate (as shown in Fig. I.) An- 

 terior edge of front strongly carinate, deeply and widely emarginate 

 in the middle opposite the labrum and less deeply so on each side. 

 Epistoma scarcely extending forwards beyond the central emargination 

 of the front, and separated from the labrum by a very distinct and 

 Jeep transverse suture. Labrum moderate, transverse. Mandibles 



