150 DR. W. B. BENHAM ON [Feb. 16, 



presented by the position and arrangement of the internal organs, 

 which I haye just mentioned, in Kynottts, and, still further, the posi- 

 tion of the few genital organs described by Michaelsen, I am inclined 

 to put a different interpretation on his " segments," and hence a 

 different enumeration of " somites." 



In K. madagascariensis the only genital organs observed are the 

 spermatheccE ; these are in a condition similar to that of MicrochcBta ; 

 they are in rows of 22, 26, and 25 small sacs along the anterior 

 margins of the "segments" 23, 24, and 25 respectirely ; the rows 

 extending nearly all round the body. 



In K. longus there are four rows of eight spermathecse — one row 

 on each side of the anterior margin of the " segments " 25 and 26. 

 In this species he observed the sperm-sacs, of which there appears 

 to be a pair in front of each of the septa vi. and vii. [" Ein Paar 

 umfangreicher Sacke, vor den Dissepimeuten vi. and vii., deutete 

 ich als Samensiicke "]. 



Now, if it be borne in mind that between the septa v. and vi. there 

 are, according to Michaelsen's mode of reckoning, two " segments," 

 namely the 16th and 17th, and between the septa vi. and vii. like- 

 wise two " segments," the I8th and 19th, we get the sperm-sacs 

 occupying a very abnormal condition indeed ; for in what Earthworm, 

 of all the many genera, do we find the sperm-sacs originating as far 

 backwards as the 16th " somite" ? ' They usually occur in any somite 

 from the eighth to the twelfth, and where there are two pairs they 

 nearly always originate in somites x. and xi., or in somites xi. and xii. 



I believe this apparently abnormally posterior position of the 

 genital organs and the other peculiarities of Kynotus can be ex- 

 plained by interpreting the external rings, not as ^'segments" but as 

 annuli ; then between every two consecutive septa in the anterior 

 part of the body we shall have not two "segments" but two annuli, 

 that is one somite, and we shall find that matters work out more in 

 accordance with what we find in other Earthworms. 



Granting that the gizzard lies in somite vi., which is a very usual 

 position for the organ in the family Rhinodrilidce (amongst which 

 Michaelsen places the worm), as well as in other families, the first 

 septum lies, not between " segments " 7 and 8, but behind somite vi., 

 the second behind somite vii., and so on ; this brings the sperm-sacs 

 into somites xi. and xii. (where they do occur in Micr. rappi, in 

 Rhinodrilus, Hormogaster, and perhaps in Bracliydrilus), and the 

 spermathecse are then in somites xv. and xvi, in K. longus, and in 

 somites xiv., xv,, and xvi. in E. madagascariensis ; and this position 

 agrees with that of the sacs in 2Jic. rappi. 



Again, the nephridia will be o)ie to each somite. Michaelsen 

 remarks on the variation in the position of the pores in the anterior 

 region of the worm, where they lie in some " segments " just behind 

 the septa, in others in the m.iddle of the " segments" ; he sees only 

 one explanation of this, that the nephridia were originally one 



^ The condition of the sacs in Geoscolex, Uroch(Bta, and Biachata is quite 

 different ; they may cxfcnd into tlie=tt somites, but onyiuatc in a more normal 

 position. 



