Fig. 34. The raphe system. (a) Simple slits of Anorthoneis. (b) Internal polar ending, showing ridges on either side of the raphe fissure and the polar helictoglossa in Pleurosigma. (c) Massive internal development of the raphe-sternum in Frustulia. (d) External raphe ending with terminal fissure extending beyond the region of the helictoglossa (arrow). (e) Fibulae subtending the raphe of a Nitzschia. (f) Central raphe endings of Gyrosigma. (g) Internal central raphe endings with ‘helictoglossa-like’ structures in Parlibellus.
No comments:
Post a Comment