72 [March, 1900. 



pieces or claspers, and the dorsal piece or uncus. Now, the Litho- 

 colletes have an additional or ventral piece, rather broader, but in 

 other respects similar to the dorsal one, and together they form a 

 pair of simple valves very like the glumes of a grass seed in form. 

 Mr. McLachlan tells me that this extra piece is frequently present in 

 the Triclwptera, but whether it is possessed by any other family in 

 the Lepidoptera T am unable to say. The other peculiarity is a want 

 of symmetry on the two sides, the left clasper being larger than the 

 right, though the disparity is more clearly shown in the pair of large 

 and curious spines (c) which spring from the bases of the claspers 

 than in the claspers themselves. It is, however, a most unequal 

 character, as may be seen even in the small group we are dealing with ; 

 in one species it may be clear and obvious, in another almost in- 

 appreciable, or quite so. The uncus and its fellow or ventral piece 

 offer no differential characters, and have, therefore, been left out in 

 the figures, as they would only obscure the essential parts, which are 

 the claspers. These have been represented attached to the chitinous 

 frame which is common to all four pieces. Preparations in abundance 

 have been made of all the species, except cydoniella, of which I was 

 able to procure only a single male ; and from dry specimens as well 

 as fresh. Moreover, not satisfied with British specimens, I have in 

 most cases examined continental ones also, and with perfect agree- 

 ment. Did one form run into another by local variation or otherwise, 

 I must have obtained some evidence of it ; but no intermediates 

 exist, each is absolutely constant, so far as anything can be said to 

 be constant in nature. The figures have been drawn under a camera, 

 and to a common scale. The great disparity, therefore, in their size 

 represents faithfully the disparity in size of the organs themselves. 

 An endeavour has at the same time been made to draw them exactly 

 from the same point of view, with the claspers lying on their edges, 

 in the position they would naturally present if the insect were being 

 looked at from above. But to get them to lie absolutely true is not 

 as easy as might be supposed, for one or other clasper, when the 

 cover glass is pressed home, usually gets a slight cant, and evidence of 

 this is present more or less in all the figures, except those of concomi- 

 telJa and blancardella. It is necessary also when dealing with bred 

 specimens to allow sufficient time to elapse after emergence for the 

 parts to harden, for if this be not attended to, some distortion of the 

 claspers from overdistension may take place, though the spines which 

 are of stouter material are not so liable to the accident. How possible 

 this overdistension may be is obvious enough, when it is remembered 



