ON THE SCAPHIUM OF GOSSE. 285 



On the Scaphium of Gosse. 



By T. A. CHAPMAN, M.D., F.Z.S., F.E.S. 



The name Scajihiion, for a certain portion of the male genital 

 armature of lepidoptera, was given by Gosse''' to a process whose exact 

 position has not apparently been understood clearly by subsequent 

 writers. At any rate, trying to understand Gosse, and to agree with 

 the interpretations usually placed on his descriptions, I have to confess, 

 that in cotnmon with various authorities, I have fallen into error, and 

 confounded the Scapliii(iii with the sternite (ventral plate) of the 

 10th abdominal segment. 



Mr. Pierce is, I believe, the only authority of any note who has 

 applied the name correctly. 



I desire to confess my error in the matter, and, if possible, to 

 make it manifest to those with whom I have been misled. 



In the genus I'apilio the scaphium is a highly-developed and 

 complicated mass between the uncus (dorsal portion or tergite of 

 10th abdominal segment) and the iedcvagus ; in all other groups it is 

 much more simple or wanting. 



The point on which I went astray was in regarding the sea phi am 

 as being subanal. This was the result of depending on Gosse's critical 

 remarks instead of on my own observations. 



Gosse, in his latest remarks on Ornitlioptera rewn/.s, Avhich he makes 

 in an appendix, but which agree with sundry other passages elsewhere 

 in his papers, distinctly asserts that the anal opening is between the 

 uncus and scaphium. He says: "In both (>. remits and O. haliphnm, 

 I have demonstrated the presence of an orifice leading from the 

 abdominal cavity between the uncus and the scaphium, and I have 

 passed a fine needle through it — though from the extreme minuteness 

 of the parts and their dry condition, the demonstration w^as not quite 

 so satisfactory as I could wish. Still I can find no anal orifice 

 possible anywhere else than here." {Trans. Linn. Soc, Zool., 2nd 

 series, vol. ii., p. 336.) Gosse does not seem to have really observed 

 the anus at all. 



My error, then, consisted in accepting Gosse's description without 

 checking it for myself in Papilio, for the organ has no very prominent 

 existence in the other groups which I have examined, and I felt no 

 doubt that a Avell-developed process between the uncus and the 

 a^doeagus must be the scaphium. 



The organ I have called the scaphium is really the sternite of the 

 10th abdominal segment. It is well-developed in the SpJiin/jidae and 

 various other families. 



Mr. Pierce and Mr. Burrows both place the scaphium where it 

 really is, above the anus, and have more than once remonstrated with 

 me for placing it below (where Gosse says it is). I don't know 

 whether they are familiar with groups in which the 10th sternite is 

 marked. 



I have now examined several Papilionidae with Mr. Burrows' 

 admonitions on the one hand, and Gosse's text and figures on 

 the other. 



The position of the anus in Fapilio appears to be at a point close 



* Trans. Linnean Soc, 2nd series, vol. ii.. Zoology, p. 275, 1883. 

 November, 1911. 



