006 On the Genus Nntykus {Mich.). 



following reasons: — The external orifices of tlie ''Neben- 

 tasclien ^^ in the bisected specimen now under consideration 

 are considerably retracted, as I have explained ; but the 

 distance between their openings and the line along which 

 the spermatliecal pore touches the bodj^-wall, which is very 

 plain, is considerable. For, while the sperniathecal pore is 

 clearly upon segment 13, the pores of the muscular appen- 

 dices are not only in the 14th segment, but some little way 

 within it. A great area would have lo be j)ulled inside the 

 body-cavity if the spermathecal pores were to be withdrawn. 

 Furthermore, the strap-like external region of the sperma- 

 thecal sac is tightly tied to the slender wall forming the 

 septum 12/13, which together with the spermathecal sac 

 itself forms a closed cavity within which lies the peculiar 

 accessory gland, referred to above, and — as I believe, though 

 I have not clearly seen them — the ovaries and the funnel of 

 the oviduct. All this complex would have to be pulled in- 

 wards if the spermatliecal pore were retracted, and it does 

 not seem possible. In any case, the spermathecal pore was 

 7iot retracted in this specimen. 



The muscular double-walled bauds lying across the sper- 

 mathecal sac, which liave been described, lie, it should be 

 added, in an oblique direction from before backwards; it is 

 possible that they represent septum 14/15, which is other- 

 wise not recognisable. Kor, for the matter of that, is the 

 next septum — i.e., 15/16. 



In the angle which lies between the muscular gizzard-like 

 region of the spermathecal sac and the anterior downwardly 

 directed external passage of the same lies a triangular- 

 shaped muscular sac, which is clearly the " Nebentasche " 

 of its side. It is not so uniformly rounded as in the less 

 mature example B ; but ends above in quite a pointed end. 

 It lies over the gizzard-like region and is marked off by a 

 deep furrow from the strap-shaped end of the spermathecal 

 sac, and by a less marked, but still quite marked, furrow 

 from a muscular layer lying across the gizzard-shaped median 

 region of the spermathecal sac. 



The two masses of muscle, thus brought into intimate 

 connection with the spermathecal sac, must presumably, 

 when contracting, tend to compress the sac and to squeeze 

 out its contents. If tins sac, as in the allied genus Stuhl- 

 vKmnia, contains a spermatophore, this might conceivably 

 be expelled by the contractions. But of such functions we 

 know nothing in these and allied worms. 



Nothing- at all corresponding to the posterior double sheet 



