The Anatomy of OpisthojMtus cinctipes. 71 



A, well-developed coxal organ was present in the specimen men-' 

 tioned above in each of the legs from the 5th to the 14th pairs : 

 inclusive. On the first 4 pairs the organ was either quite absent 

 or (on the 4th pair) present in a very rudimentary condition. A 

 small coxal organ was present also on the 15th pair, but quite 

 absent from the 16th pair {cf. fig. 11, which was drawn from the 

 same specimen). 



In another male from Eichmond (also drowned) the coxal organ , 

 was absent from the 1st and 2nd pairs of legs, present on the 3rd 

 right leg but absent from the left, quite absent from the 4th pair,, 

 very distinct on the 5th to 15th pairs inclusive, and absent from the 

 16th pair. 



In a large female from Eichmond (drowned) the organ was absent 

 from the first 5 pairs of legs, present and normally developed on the 

 6th to 14th pairs, rudimentary on the 15th, and absent from the 

 16th pair. 



In a large female from Dunbrody (in spirits) a distinct coxal 

 organ was present on each of the first 15 pairs, but absent from 

 the 16th pair of legs, those on the first 2 pairs being small, but 

 those on the other legs very large and well developed. 



The conclusion I draw from the above and from an examination; 

 of a number of other spirit specimens is that the coxal organ is 

 normally absent from the last and often also from a varying number 

 of the anterior pairs of legs (up to the first 5), but present on the 

 remaining pairs. 



In the living animal the coxal organ presents, when fully expanded^ 

 a smooth, somewhat translucent, shiny area, and appeared to be 

 quite dry upon the surface. The whole organ can be completely 

 retracted into the interior of the leg and expanded again apparently 

 at the will of the animal, as I have repeatedly observed while 

 handling living specimens. When the organ is retracted it forms 

 a deep cavity with an oval to slit-like opening, which runs parallel 

 to the axis of the leg and may be almost completely closed by the 

 apposition of the adjacent papillose surfaces, bordering its anterior 

 and posterior margins. In this case the organ becomes effectually 

 hidden, and it is then impossible to tell from a mere external 

 inspection whether it is present or not. 



In spirit specimens the organ appears in all stages between 

 complete retraction (fig. 23) and nearly complete expansion (fig. 22), 

 although never so fully expanded as in drowned specimens. A 

 very common condition is that shown in fig. 13, in which the 

 peripheral parts are evaginated, but the central part retracted to 



