310 t)EEP-SEA DIATOMACEiE MANN. 



similarity is disiilayed in some li^mcs of tliese two forms, as in those of 

 Van Heurck, but an examination of the diatoms will disclose a dift'er- 

 eiice too wido to admit of tln^ir bearing' tlu'. same name. 



Podosira conipressa West. (Mo('l)iiis'8 rhitos, pi. 31, lig. 11. rritcbard'H Inf., i)l. 

 8, fig. 34, pp. 15 and 938.) Very scarce. 



This j^enus and HyalodLscus need to be united. 



Podosira maculata W. S. (Sinitli's B. 1)., )>1. li), lig. 328, p. 54. Sclimidi's Atlas, pi. 



139, iig. 7.) Common. 

 Pyxilla Baltica (Irnu. (Van Hourck's Syn., pi. 83, liga. 1,2.) Trequent. 

 Raphoneis amphiceros E. (Vau Heurck's Syn., pi. 36, ligs. 22-28, pi. IIG, lig. 17.) 



Freqnont. 

 Raphoneis amphiceros, var. rhombica Grnn. (Van Heurck's Syu., i)l. 3(5, ligs. 



20-21. Mocbins's plates, pi. 1, fig. 10.) Scarci^ 



Grunow lias placed the A', rhombns of Koger as a variety of amphi- 

 cei'os, from which it differs only slightly. 



Raphoneis gemmifera Elirb. (Pautoesek's Hung., pi. 12, fig. 104, etc.) Very com- 

 mon. 



Raphoneis surirella (iriin. (Van Heurck's Syn., pi. 30, figs. 2G-27B.) Frequent. 



Rhabdonenia minutuni Kg. (Van Heurck's Syn., pi. 54, Hg. 21.) Fretiuent. 



Rhizosolenia styliformis Bright. (Vau Heurck's Syn., pi. 79, figs. 1-5.) Very 

 scarce. 



Schizonema vulgare Tliw. (Van Heurck's Syn., pi. 17, fig. G.) Scarce. 



Were the genus t^^eltizonemu not a fictitious one it would be well to 

 take this form out of it, as it luis no structural unity with any other 

 members of that genus. But iSchizonema ought to be relegated to 

 Namciila, where it belongs. 



Stauroneis anceps Elirb. (Van Heurck's Syn., \)\. I, figs. 4-8.) Scarce. 

 Stauroneis PhcBnicenteron Ehrb., var. gracilis (=^S. gracilis W. S.). (Smith's 



B. I)., pi. 19, fig. 18G. Van Heurck's Syn., i)l. 4, fig. 2.) Frequent. 

 Stauroneis Smithii (iruu. (Vau Heurck's Syn., pi. 4, lig. 10.) A'ery scarce. 



Wm. Smith figures this correctly, pi. 11), tig. 19;3, but incorrectly 

 calls it " IS. linearis E." The latter is given by Van lleurck, pi. 4? 

 fig. 8, as a variety of S. anceps. Grunow has named it after the first 

 author, giving its ('(urect figure. It seems to be truly hyaline. 



Stephanodiscus Hantzschianus (iruu. (Clcve's (1880) Arctis., i)l. 7, fig. 131. Xim 



Hourck's Syn., \A. 95, fig. 10.) Very scarce. 

 Stephanogonia Danica (!run. (Van Heurck's Syn., pi. 83 bis., figs. 7-8.) Scarce. 



Tlie form here louiul is a variety of the above, its ridged lines, 

 radiating from the central apex, being more numerous and less i)laiuly 

 visible. 



Stephanopyxis corona I'^lirb. (Schmidt's Atlas, pi. 123, figs, 10-17.) Scarce, 

 Stephanopyxis turris Kalfs. (Van Heurck's Syn., i)l. 83 ter., fig. 12; Schmidt's 



Atlas, 1)1. 130, figs. 42-43; Pritchard's Inf., pi. 5, fig. 74, and p. 82G.) Frequent, 

 Surirella minuta Breb. (Vau Heurck's Syn., pi. 73, figs. 9-10.) Frequent, 

 Surirella ovalis Breb. (Vau Heurck's Syn., pi. 73, figs. 2-4.) Common. 

 Surirella recedens A. S. (Schmidt's Atlas, pi, 19, tigs. 2-4, pi, 24, fig, 28.) Scarce. 

 Surirella tenera Greg. (Schmidt's Atlas, pi. 23, figs. 7, 9.) Scarce, 

 Syndendrium diadema E. (Moobius's I'lates, pi. 8, tigs, 49-52,) Frequent. 

 Synedra delicatissima W. S., var. mesoleia (irnn. (Vau Heurck's Syu., pi. 39, tig. 



G.) Scarce. 



