MALFORMATION OF THE GENITALIA OF HYDRCECIA PALUDIS. 171 



Description of Plate IV. 

 1. MajUormed a.]}T[)endsiges oi Hydroecia paludis x 12^. 

 2 and 3. Normal t? and ? appendages, x 12J, for comparison. 



The Malformation of the Genitalia of Hydroecia paludis. {With 



one plate). 

 By F. N. PIERCE, F.E.S. 



The rudimentary organs of The Rev. C. R. N. Burrows' wonder- 

 fully malformed specimen of Hydroecia paludis go a long way to 

 confirm the opinion I have previously held, that the various parts of 

 the genitalia are originally separate and distinct organs in the various 

 species, but are often fused together, and in many cases this fusion 

 sinks the identity of the organ to such an extent as to make the 

 student consider the parts as additional organs, whereas they are 

 either more highly developed or are thrown back to their original form. 



In the specimen under consideration the uncus No. 1 is normal ; 

 tho anus No. 2 (called by Dr. Chapman the scaphium) is normal ; the 

 peniculus No. 3 is normal ; Dr. Chapman's No. 4, which in the photo- 

 graph appears to be a separate arm, is merely the thickening of the 

 edge of the tegumen, from which springs the peniculus. Below these 

 parts we enter into difficulties, because the remainder of the organs 

 are in a rudimentary or partially formed condition. 



The valva is usually considered to be a single organ, and I have 

 been criticised in giving names to the parts ; for example sacculus, 

 harpe ( = clasper), etc. This is more apparent than real. The valvae 

 are, in fact, composite structures made up of a number of distinct and 

 separate organs springing from separate bases, as the specimen under 

 notice well illustrates. And in order to piece together the valvje we 

 must collect the parts. It is curious to notice in the mount these 

 parts are largely reversed, that is, they point towards the head instead 

 of the tail of the moth as normally. 



The paired organs, No. 6 of Dr. Chapman's Fig. 2, are the 

 sacculus ; this is often quite separate from the valvae in other species, 

 and evidently is a separate organ previous to fusion ; below this is the 

 left hand valva proper. No. 8 (without the cucullus, which is evidently 

 normally attached to the costal arm). It will be noticed there is 

 only one valva developed, that of the left side ; in the mount the 

 inner margin is above, not below, the spines from the edge being 

 quite normal and identical with those of paludis. The saccus 

 (vinculum) is normal. 



We now come to the organs that are contained inside the body. 

 In respect to the valva, so far the parts identified are the valva proper, 

 and the sacculus. Of the missing parts the cucullus is enclosed in its 

 sac, and in the photograph is immediately under the saccus and 

 extends downwards, projecting from the costal arm. Towards the 

 base of this sac is the editus. The harpe (clasper) is very rudimentary, 

 but the shape is plainly visible with its short heel and long pointed 

 toe. There is, as Dr. Chapman states, only one Clavus No. 5, and 

 the ^Edoeagus No. 7 is practically normal, with its vesica and cornuti 

 of paludis form, and connected therewith is the fairly normal juxta, 

 the front plate as well as the scobinated membrane behind the 

 .iEdceagus being well developed. The remaining structures consist of 



