﻿SOME REMARKS ON THECLA ^SCULI. 207 



I appear to have agreed with him, without very careful consideration. It 

 is, however, a part of tlie sohd tedeagus, and it forms a portion of the 

 extremity' of the organ, from which the vesica begins to evert. 



Nevertheless, I believe Mr. Kayward and myself were so far right that, 

 though not moveable with the eversible membrane, but fixed to the tube of 

 tlie aideagus, it is morphologically as much a cornutus as a portion of the 

 a^deagus proper. The ductus may be cliitinised more or less and in different 

 forms, so that it is, in a sense, accidental whether some particular portion 

 of the ductus be solid aedeagus or eversible membrane (with or without 

 "cornuti"), or, as here, present a somewhat ambiguous intermediate 

 condition. 



The little group of Theclas to which it belongs have a very similar 

 structure, varying of course a good deal in details and in the proportion 

 of parts. 



In the rough sketches from camera outlines of these parts in T. spini 

 and T. ilicis it will, I think, be clear, that the end of the aedeagus divides 

 into three chitiuous processes. I have selected T. spini, instead of any other 

 species, to illustrate this, as it seems nearer to ilicis and cesculi than any of 

 them. I have selected specimens in which the three processes happen to 

 diverge considerably. This is probably due to pressure of the specimen in 

 mounting, and may be an attitude assumed when the organ is in use, but 

 I fancy in an ordinary position of rest the three processes are more parallel 

 to each other (as in Plate IX.). The other allied species, as judged by the 

 structure of the aedeagus, are almost resolved into acacice only, in which the 

 structures B and C are very similar to each other, not unlike C as formed in 

 ilicis, but both with much longer free portions. 



Acacice associates itself with ilicis and cesculi in having both these 

 processes (B and C) apparently solidly attached to the chitinous cylinder of 

 the asdeagus. In j^:)r?Mij", the other species apparently belonging to this 

 group, there is what is almost a fundamental ditferenca. The two processes, 

 if we are so to recognise them, in primi are not solidly attached to the 

 sedeagal tube ; but are movable with the vesica, and might be called 

 cornuti, so nearly so as to quite excuse the mistake of at first believing 

 them in ilicis to be cornuti. It is difficult to doubt that the two processes 

 in pruni are homologous with those in ilicis, yet B is a small spiculate 

 piece attached to the vesica, with the solid stem, as seen in ilicis, reduced to 

 quite a soft membranous ribbon ; C is larger, and has a slender stem un- 

 attached to the fedeagus proper. Both protrude with the vesica and separate 

 from each other, but maintain when everted the same direction as when at 

 rest, i. e. their spicules continue to point outward, and are not turned round 

 so as to point inward as in typical cornuti. When at rest both spicular 

 bodies lie closely together in the centre of the ffideagus near its extremity'. 



Fig. 1 represents ilicis ; I have not given cesculi, since it differs from 

 ilicis only in the extremity of the process I have marked B. 



Fig. 2 represents sjjini ; A is the extremity of the tube of the aedeagus ; 

 the edge of what appears as the free surface (against the letter A) has 

 extremely fine spiculations in all these species. B is the process that, in 

 ilicis and cesculi, affords the differentiating specific characters. C is a 

 process that, in ilicis and cesculi, has the appearance in most preparations 

 of a flat plate with a lancet-shaped end lying flat within the asdeagus. In 

 fig. 1 it is seen rather sideways, and shows that it has an external free 

 margin. D is a portion of the eversible membrane (vesica), partially 

 extended and exposed, in accordance with the apparently porrected positions 

 of processes B and C. Normally at rest these processes are probablj' parallel 

 with the axis of the aedeagus ; C, fig. 2, is obviously in a specially everted 

 position. 



The process B of fig. 1 (letters are placed on fig. 2) is the one in which 

 there is a definite difference, apparently constant, between ilicis and cesculi. 



Mv original difficultv with regard to feeling clear as to ■\\hat the diliercnco 



