252 Mr. S. H. Scudder on the 



abdomen, it is seen to be formed mainly of two slender 

 blades, curving in opposite senses, which lie under the 

 protection of the anterior processes of the ninth segment, 

 but, when they pass forward, dilate into triangular ex- 

 pansions which nearly fill the lozenge-shaped space left 

 vacant between the curved base of the anterior processes 

 of the ninth segment (following the similar curve of the 

 eighth segment) and the slightly emarginate apex of the 

 seventh ; at their base they appear to be attachments of 

 the seventh segment ; the opposite sides of the triangular 

 basal expansion are thicker than the middle, as if there 

 were a two-branched basal attachment connected by a 

 slight membrane to give greater support and rigidity to 

 the attachment. 



This organ, which, so far as I know, has no homologue 

 whatever among Lepidoptera, seems to lie in just the 

 place and to be of just the form to serve as the apparatus 

 for moulding on its interior the abdominal pouch of the 

 female out of the secretions which flow either from it or 

 through it or around it from glands in close connection 

 with it ; and consequently I suggest for it the name of 

 peraplast {Ttnpa, TrKaa-aca) , indicative of its use. The at- 

 tachments and the mechanism by which it may act, 

 together with the precise position and relation to it of 

 the adjoining secretory glands, can of course only be 

 told from fresh specimens ; and fresh specimens would 

 doubtless serve also to correct in some particulars this 

 preliminary description. It will perhaps be found that 

 the "membrane" mentioned by Thomson " containing a 

 dark green fluid" is an evaginable gland extended from 

 near the base of the false claspers (precisely as the 

 evaginable pencil of bristles in Anosia), and that when 

 it protrudes beyond their tip — as Thomson's description 

 would seem to imply — it secretes from its inner surface 

 the material of which the pouch is formed, which is then 

 moulded into shape by the scimitar-shaped perai)last ; 

 this must have an extensile movement, surpassing even 

 that of the true claspers. This is a j)oint which only an 

 examination, first of living males and next of pairs in 

 union, can fully satisfy : and it will then remain for the 

 histologist to scrutinise the organs themselves. 



The problem still remains, to understand the purpose 

 of the feminine pouch in Parnassius, and the homologous 

 flaps in Eurijades. Although they take on a definite 



