232 Dr. E. A. Cockayne on 



The normal bursa copulatrix in A. coridon consists of 

 a tube of uniform width ending in an oval dilatation, 

 the caput bursae. It arises from a point slightly below 

 the apex of a rounded chitinous prominence, broader at the 

 base than the apex and flattened in its antero-posterior 

 diameter. This is supplied with muscles for extruding 

 the prop and rein of Chapman. These organs are con- 

 tinuous with the tubular part of the bursa, and at the 

 point of junction the ductus bursae arises. The ductus 

 in argns is double the length of the tubular part of the 

 bursa. The first half is narrow and the second half which 

 opens into the vagina is much wider. 



In argtis bursae like those of coridon were found in 25 

 out of 29 normal females, i. e. females with no male 

 characters, but only in 8 intersexes out of 26. There 

 were minor variations in the length and width of the 

 tubular part, and in the size of the caput, in specimens 

 which I have regarded as normal. 



In the intersexes abnormalities of the tubular part 

 were common. The proximal part of the tube arising 

 from the basal prominence was frequently more or less 

 dilated, and the dilatation extended a variable distance 

 up towards the caput. Then it became suddenly narrower, 

 forming a tube thinner than the tubular part of a normal 

 bursa. This thin part was of considerable length in some 

 and in others formed a mere constriction between the 

 dilated part and the caput. In one there were two con- 

 strictions in the tubular part, and in another one con- 

 striction in the tube and a second in the caput itself. 

 In one case the bursa was lying very much twisted and the 

 tubular part, narrow at its origin, became gradually wider 

 and then suddenly constricted just below the caput, whicli 

 was quite transparent. In one specimen, which dried 

 after having been in alcohol, the dilatation became full of 

 air and was seen to have very thin walls. Several appeared 

 to be like this, but in others a narrow inner tube ran down 

 the tubular part of the bursa and the dilated part almost 

 to its point of origin. In a normal bursa this inner tube 

 can be traced from near the point of origin up the tube 

 into the caput, where it expands into an oval termination. 

 In Rnmicia phlaeas there is always a short, broad dilata- 

 tion of the bursa before the narrow tubular part com- 

 mences, and perhaps this corresponds to the proximal 

 dilated portion of the bursal tube in these abnormal argus. 



