CONTAINING DIATOMACEOUS EXUVIM. 39 



It is a fresh-water form, and I have found it in many recent 

 gatherings. (212.) 



Fig. 4. Amphora Arcus, W. G. This fine form has not 

 occurred in its entire state, but is frequent in the detached 

 condition. The halves have precisely the form of a strung 

 bow, often very elegantly curved. The striae are coarse and 

 moniliform. I have no certain means of a-jcertaining its 

 habitat, but I suspect it to be marine. (213.) 



Fig. 5. Amphora iacurva, W G. This is also a very pretty 

 form, most probably marine, and occurring detached, like the 

 last. The strise are very much finer than in A. Arcus. (214.) 

 Fig. 6. Amphora angularis, W. G. This is a striking form, 

 and unlike the two preceding It occurs now and then com- 

 plete, when it exhibits short square apices. It has a slight 

 constriction in the middle. Habitat unknown. (215.) 



Fig. 7. Cocconeis transversalis, W. G. This neat little form 

 is distinguished from the other species of the genus by having 

 fine transverse striae. Its form is a pure oval. Habitat not 

 known. (216.) 



Fig. 8. Cocconeis speciosa, W. G. This form is nearly allied 

 to C Scntellum, but is usually smaller, and has somewhat of 

 an angular form. The chief distinction lies in the striae, which 

 are much less numerous tlian in C. Scntellum, not exceeding 

 12 in •001", and they are formed of much fewer and much 

 larger granules. Like C. Scntellum it occurs both with and 

 apparently without a margin ; and it might be taken for a 

 variety of that species, but for the number and peculiar 

 character of the striae I have closely searched several slides 

 of marine origin, full of CoccoJieis Scutellum of every degree 

 of development, but I have not found in them one example of 

 C speciosa. I therefore regard it as a distinct species. (217.) 

 Fig. 9. Cocconeis distans, W. G. This very beautiful form 

 is at once characterised by the equal size of the dots or gra- 

 nules, and their great distance from each other, so that it almost 

 loses the aspect of striation. The form is purely oval. (218.) 

 Fig. 10. Cocconeis costata, W. G. This is a fourth new 

 species of the genus, and is at once characterised by its very 

 strong and entire costse, which seem to be double lines or 

 bands, expanding a little externally. It is a perfectly well- 

 marked species. The habitat of this, as well as of the two 

 preceding forms, is unknown, but they are probably of marine 

 origin. (219.) 



Fig. 11. Etipodiscns, qu ? Ralfsii y6. This disc, which is 

 not unfrequent, has a finely-radiate surface, the radii composed 

 of small puncta, as in E. Ralfsii. But there is no trace of the 

 pec\iliar blank spaces among the rays, which, so far as I know, 



