94 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



and outer area by a crude hyaline ring about midway between the 

 center and edge of each valve, there is no central scar or other in- 

 dication that the frustules grow attached in filaments, nor have I 

 ever found them so united. If they have that habit of growth, the 

 fact would go far toward fixing the position of this diatom in Melosira 

 As it is, it looks very unlike any member of that genus but does not 

 seem to fit into any other assignment. 



MELOSIRA MEDITERRANEAN Grunow 



(Van Heurck, Synopsis, pi. 91, figs. 3, 5.) 



This also is a doubtful member of this genus. De Toni (Syl. Alg., 

 p. 1157) refers it to STceletonema, to which it has about equal affinities 



Genus NAVICULA Bory 



NAVICULA ABRUPTA Gregory, var? 



(Schmidt, Atlas, pi. 2, fig. 34, misnamed, and compare pi. 3, fig. 21.) 



NAVICULA ACROSPHAERIA(Brebisson) Kiitzing 



(Schmidt, Atlas, pi. 43, fig. 16.) 



The union with N. tabellaria Kiitzing in De Toni's Sylloge Algarum, 

 page 26, is unwarranted. Its presence here is as a fresh-water inter- 

 polation in some of the Philippine Islands bays. 



NAVICULA AESTIVA Donkin 



(Donkin, Diat., Northumb., p. 32, pi. 3, fig. 18; Donkin, Brit, Diat., pi. 1, fig. 3.) 



NAVICULA ANGULOSA Gregory 



(Gregory, Glenshira Diat.. pi. 5, fig. 8; Donkin, Brit. Diat., pi. 4, fig. 4.) 



Van Heurck and De Toni put this as a variety of N. palpebralis 

 Brebisson, an admissible assignment. 



NAVICULA ANTILLARUM (Cleve) Mann 



(Cleve, W. I. Diat., p. 8, pi. 2, fig. 11.) 



Cleve suggests that this diatom may belong to Navicula, but pre- 

 fers his new genus, Alloioneis. As with Van Heurck, Schmidt, and 

 others, I do not recognize the latter as an3 T thing but a subgeneric 

 division of Navicula, the alternative of Cleve is here adopted. I see 

 nothing but the inadequate fact of a lightly diagonal rhaphe to 

 sustain Pelletan's idea of this belonging to Scoliopleura, a view fol- 

 lowed by De Toni (Syl. Alg., p. 265). 



NAVICULA APPROXIMATA Greville 



(Edin. N. Phil. Journ., vol. 10, pi. 4, fig. 10; Greville, Cal. Guano, pi. 4, fig. 4.) 



Grunow's var. substauroneiformis in Schmidt's Atlas, plate 2, fig- 

 ures 20-21, was also found and is another case of forms peculiar to 

 Campeche Bay and the Philippine Islands. 



