122 P. T. CLEVK, SYNOPSIS OF TFIE NAVICULOID DIATOMS. 



the latter genus much larger. Several species of Frustulia (as F. vulgaris) live enclosed in gela- 

 tinous tubes and have been considered as belonging to a separate genus (Colletonema Thaw.); 

 others live in gelatinovis masses {Frustulia Ag., Eiib., Kutz.). No generic distinctions may be 

 founded on such characteristics. Br^bisson founded 18(58 (Ann. de la Soc. phytol. et microsc. de 

 Belgique, Vol. I p. 201) the genus Van Heurckia on the peculiar structure of the central nodule 

 and the median line. With Pfitzer I am inclined to retain the old name Frustulia. 



Artificial hey. 



Valve rliomboiil to laiiceolati; 2. 



— linear to elliptic-linear 4. 



. 3ize small. L. 0,028 to 0,03 mm F. styriaca Grun. 



larger. L. 0,0 5 or more 3. 



., j Median stria; slightly radiate F. vnlyaris Thw. 



2. {^^ 



J Me 



1 — — parallel F. rhomboides Ehb. 



{ 



J Terminal nodules near the margin F. interposita Lewis. 



— distant from — F. Lewifilana Grev. 



1. F. styriaca Grun. (1880). — V. narrow rhombic-lanceolate. L. 0,o28 to 0,o3; B. 0,005 

 to 0,ooG mm. Central nodule elongated. Stritc slightly radiate, also at the ends, about 24 (middle) 

 to 27 (ends) in 0,oi mm. — Nav. {VanJmircUa?) styriaca Grun. V. H. Syn. PI. XVII f. 7, 8. ■ 



Fresh water? 



1 have not seen this species, which has the appearance of a small F. rhonihoides. 



2. F. vulgaris Thw. (1847). — V. narrow-lanceolate, with subrostrate, obtuse ends. L. 

 0,05 — 0,07; B. 0,011 mm. Central nodule elongated. Stria* 24 (middle) to 34 (ends) in 0,oi mm., 

 slightly radiate in tbe middle, transverse at the ends. Frustules enclosed in unbranched gelatinous 

 tubes. — Colletenema vulgaris Thw. Ann. N. H. (2) I PI. XII f. 4. W. Sm. B. D. II p. 70 PI. 

 LVI f. 351. Grun. Banka D. II f. 15. Nav. dirhynchus Donk. B. 1). PI. V f. 3 (1871) Ehb.? 

 Kiitz? Vaiiheurckia vulgaris V. H. Syn. p. 112 PI. XVII f. 6. 



Fresh water: Sweden! Norway! Finland! Saxony! Belgium (V. H.), Switzerland (Brun.), 

 Siberia! Japan! Bengal! Australia (Orara River, Blue mountains etc.)! Tasmania! Ecuador! 



Var. asyninictrica (Jl. — V. elliptical, asymmetrical, with obtuse ends. Median line excen- 

 tric, more approximate to the less convex margin. Terminal nodules at some distance from the 

 ends of the valve. Stria; 22 to 30 in 0,oi mm., somewhat radiate in the middle and closer at 

 the ends, punctate; puncta arranged in longitudinal undulating rows, 19 to 23 in 0,oi mm. — 

 PI. V f. 29. 



Brackish water: Sierra Leone! Cameroon! Tasmania! Newark N. Jers. fossil (Champlain epoch)! 



3. F. rhomboides Ehb. (1843). — V. rhombic-lanceolate, with obtuse ends. L. 0,o7 toO.ie; 

 B. 0,0 15 to 0,03 mm. Central nodule small or ehmgated. Transverse striai parallel, 23 to 24 in 

 0,01 mm.; longitudinal striffi 20 to 25 in 0,oi mm. — Nav. rhomboides Ehb. Am. Ill: 1 f. 15? 

 W. Sm. B. D. I PI. XVI f. 129. Grun. Banka D. PI. II f. 14. Vunheurehia rhomb. Breb. Ann. 

 Soc. phyto. et micr. de Belgique Vol. I p. 204 (18(58). V. H. Syn. p. 112 PI. XVII f. 1, 2. 



Fresh water: Sweden! Finland (from Russian Lapland to Abo)! England! Belgium (V. H.), 

 Bengal! Australia (Daintree River, Blue Mountains)! New Zealand! Greenland! Canada! Sierra 

 Nevada! White Mountains! Demerara River! Brazil! 



Var. lineolata Ehb. (1843). — V. with several coarse longitudinal furrows. — N. lineolata 

 Ehb. Am. PL I: 3 f. 4 a? M. G. PI. XVI: 1 f. 3 etc. 



Fresh water: Sweden (Degernas, fossil)! Bengal! New Zealand, fossil! 



Var. orcgonica Cl. — V. narrow. L. 0,i; B. 0,oi5 mm. Transverse striae 30, longitudinal 

 25 in 0,01 mm. 



Fresh water: Oregon, fossil! 



