Rev. T. R. R. Stebbing on new Species o/* Amphithoe. Ill 



Fig. 11. Mother cell of bihamate spicule, containing a single spicule: 

 a, cell-wall ; b, nucleus ; c, bihamate. 



Fig. 12. Inequianchorate spicule, full-grown : «, lateral view ; b, front 

 view. 



Fig. 13. Mother cell of inequianchorate spicule at a very early stage of 

 development, when the embryo spicule is in the equi&nchor&te 

 form : a, cell- wall ; b, spicule ; c, the same amplified to show the 

 e^irt'anchorate or hooked ends. 



Fig. 14. The same, where two individuals were in one cell. 



Fig. 15. The same, where the cell has become polymorphic. 



Fig. 16. The same, in a more advanced stage, where the spicule has be- 

 come i'tte^'anchorate : a, cell-wall ; b, nucleus ; c, inequi- 

 anchorate spicule ; d, the same, amplified to show the nucleus 

 and granuliferous state of the cell- wall. 



Fig. 17. Microciona atrosanquinea, Bk., spermatozoid-looking bodies in. 

 Scale l-24th to l-6000th of an inch. 



Fig. 18. The same, single one. Scale l-12th to l-6000th of an inch : 



a, head and granule ; b, cilium. 



Fig. 19. The same ; group of four together. Same scale. 



Fig. 20. The same. Scale of l-4th to 1-G000th of an inch : a, head ; 



b, granule ; c, cilium. 



Fig. 21. Grantia compressa ; spermatozoid-looking bodies. Scale l-24th' 

 to l-6000thofaninch. 



Fig. 22. The same, single one. Scale l-6th to 1-G000th of an inch. 



Fig. 23. The same. Scale l-3rd to l-6000th of an inch. 



Fig. 24. Halisarca Dujardinii; spermatozoid (?) bodies. Scale l-24th 

 to l-6000th of an inch. 



Fig. 25. The same ; group of four in a cell. Same scale. 



Fig. 26. The same : a, individual attached to a group of sponge-cells by 

 the head ; b, rim ; c, granule ; d, cilium ; e, the same, showing 

 inflation of the rim opposite the cilium ; /, lateral view of head ; 

 g, cap-like projection of centre of disk ; h, individual attached 

 to a group of sponge-cells by the end of the cilium, rendered 

 bulbous under polymorphism ; i, polymorphic state with shrunk- 

 up cilium. 



XIV. — On some Species of Amphithoe and Sunamphithoe. 

 By the Rev. Thomas R. R. Stebbing, M.A. 



[Plates XL & XII.] 



It will be seen by the following descriptions how very closely 

 allied these two genera are to one another, and how closely 

 allied also are certain species within the genera. It will be 

 seen likewise that some readjustment is probably necessary. 



A new species is added to the genus Amphithoe, and one 

 which appears to have been partially, but only partially, 

 described before as a species of Amphithoe is found to have 

 a hooked telson, which will transfer it to the genus Sunam- 

 phithoe ; but this species, not content with a single hook to 



