vol 



gjj^^'] PROCEEDINGS OF THE NATIONAL MUSEUM. 307 



Tliei-e is not sufficient warrant for M. Van Heurck according to this 

 form the generic name '■'■ Roperia.^'' 



Fragilaria capucina Desuia/,. (Smith's V>. D., pi. 35, fig. 296.) Common. 

 Fragilaria Schwarzii Gruii. (Van Heurck's Syn., pi. 44, fig. 24.) Very scarce. 



The (lifieren(;e between this and F. pacijica Grim, is too slight to war- 

 rant their separation. 

 Gomphonema sphaerophorum Elirb. (Van Heurck's Syn., pi. 23, fig. 30.) Scarce. 



This is tlie same as G. lagenula Kg. See Van Heurck's Syn., pi. 25, 

 figs. 8-0. Rails rightly unites the two. Pritchard's Inf., p. 889. 



Grammatiphora macilenta W. S. (Smith's B. D., pi. 61, fig. 382, p. 43. Van 



Heurck's Syn., pi. 53, tig. 16.) Frequent. 

 Hemiaulus polycistinorum Ehrb. (Schmidt's Atlas, pi. 143, figs. 23-29.) Frequent. 

 Mastogloia apiculataAV. S. (Smith's B. D., pi. 62, fig. 387, p. 65.) Very scarce. 



This genus should be included under Cocconeis. It differs but 

 slightly in the presence of marginal loculi, which are frecpiently quite 

 indistinct. 



Melosira ornata Grun. (Van Heurck's Syn., pi. 91, fig. 20.) Frequent. 

 Melosira sulcata Kg. (Van Heurck's Syn., pi. 91, fig. 18.) Frequent. 

 Melosira varians Ag. (Van Heurck's Syn., pi. 85, figs. 11-15.) Frequent. 

 Navicula abnormis Cast. (Challenger Exi>., pi. 28, fig. 19, p. 27.) Freciuent. 



This diatom is possibly only a variety of JV"^. ajn-s ])onk. as figured in 

 Schmidt's Atlas, pi. 12, fig. 17, and pi. G9, fig. 41. I have, liowever, 

 found it to be very constant in form and fretpient in this gathering, 

 thus agreeing with the experience of Conte Castracane (p. 27). The 

 name, however, is unfortunate, as it had been bestowed on a totally 

 different diatom by Grunow. See Cleve's (1880) Arctischen, pp. 46, 47. 

 Also Cleve and Mollus Types No. 142. 



Navicula Americana E., variety. (Ehrenherg's Mik., pi. 2-2, fig. 16; O'Meara I. D., 



pi. 30, fig. 30.) Very scarce. 

 Navicula aspera Ehrb. var. Intermedia Grun. (Schmidt's Atlas, pi. 48, fig. 14.) 



Frequent. 

 Navicula bisulcata Lag. (Sclimidt's Atlas, pi. 49, figs. 15, 16.) Scarce. 

 Navicula borealis Ehrb. (Schmidt's Atlas, jd. 45, figs. 15-21.) Scarce. 

 Navicula caribcea Cleve. (Schmidt's Atlas, pi. 6, figs. 10-12.) Frequent. See note 



under next species. 

 Navicula clavata Greg. (Donkin's B. D., pi. 2, fig. 8 ; Schmidt's Atlas, pi. 3, fig. 13.) 



Frequent. 



This diatom, of which the typical form and three well-marked varieties 

 are found in this gathering, is frequently confused with the i)receding 

 species iV^. (Yn'/^rtvrof Cleve. Schmidt, after giving the correct figure 

 for N. caribcea in i)l. (>, figs. 10-12, applies the same name to the pres- 

 ent species, as in pi. 2, fig. 17, and pi. 70, fig. 48. That the true jV. 

 carlhcm is the one figured in pi. 6, figs. 10-12, is proven by the fact 

 that Cleve refers to this figure in his ^' Vega Diatoms," p. 496. 



1 must add that it would be better to include -K. clavata with all its 

 varieties under N. lyra Ehrb. 



Navicula cluthensis Cleve. (Cleve's (1880) "Arctischen," pi. 2, fig. 49.) Scarce. 

 Navicula distans W. S. (Schmidt's Atlas, pi. 46, fig. 12.) Common. 



