1889-90.] Mr F. E. Beddard on Structure, of Oligochceta. 7 
f 10. The testes are either (M. Barwelli) in segment IX, attached 
to posterior wall, or else in segment X, attached to front wall. 
11. The sperm sacs (one pair) are in segments IX or X — in 
correspondence with position of testes ; their cavity is undivided. 
+12. The vas deferens funnels , in accordance with the varying 
position of the testes, open into IXth or Xth segment. 
13. The atrium opens between segments X/X I; it has precisely 
the structure of the atrium of Rhynchelmis. 
+14. The oviducts are in segment XI; in the individual which 
probably belongs to a species distinct from M. Barwelli , the oviducal 
funnel is spread along the anterior face of the septum separating 
segments XI/XII. 
15. The spermathecse are a single pair in VIII; each is a small 
sac with a very long coiled duct. 
These points are in my opinion sufficient to render it necessary to 
regard Moniligaster as the type of a distinct family, not, as Rosa 
believes, of the Terricolse, but as equal to the Terricolse, Lumbri- 
culidse, &c. This family has evident relations on the one hand to 
the Terricolae, and on the other to the Lumbriculidse ; its affinities 
however, to any one family of the Limicolse are not marked. 
These matters are discussed in some detail in the paper, and form 
its concluding portion. 
On Self-conjugate Permutations. By Thomas Muir, 
M.A., LL.D. 
(Received Sept. 3. Read December 16, 1889. ) 
1. The conception of conjugate permutations appears to be due 
to Rothe.* The definition may be expressed thus: — Two permuta- 
tions of the numbers 1, 2, 3, . . . , n are called conjugate when each 
number and the number of the place which it occupies in the one 
permutation are interchanged in the case of the other. For example, 
tne permutations 
3, 8, 5, 10, 9, 4, 6, 1, 7, 2 (A) 
8, 10, 1, 6, 3, 7, 9, 2, 5, 4 (B) 
* “ Ueber Permutationen, in Beziehnng auf die Stellen ihrer Elemente,” 
Sammlung combinatorisch-analytischer Abhandlungen, herausg. v. C. F. 
Hindenburg, ii. pp. 263-305. 
