122 P. T. CLEVE, SYNOPSIS OP THE NAVICULOID DIATOMS. 



tlie 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 (UoUetonema Thaw.); 

 others live in gelatinous masses {Frustulia Ag., Ehb., Kutz.). No generic distinetions raay be 

 founded on such characteristics. Brébisson fouuded 1S68 (Äun. de la Soc. pbytol. et microsc. de 

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

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



'■{ 



Ärtificial hey. 



Valve rliomboid to lauceolate 2. 



— linear to elliptic-linear 4. 



/ Size small. L. 0,028 to 0,03 mm F. styriaca Geun. 



\ — larger. L. 0,05 or more 3. 



„ I Median striae slightly radiate F. vulgaris Thw. 



' \ — — parallel F. rhomboides Ehb. 



, Terminal nodules near the margin F. interposita LEwas. 



— distant from — F. Letfisiana Geev. 



J Termir 



1. F. styriaca GtRUN. (1880). — V. narrow rhombic-lanceolate. L. 0,028 to 0,o3; B. 0,ood 

 to 0,006 mm. Central nodule elongated. Strise slightly radiate, also at the ends, about 24 (middle) 

 to 27 (ends) in 0,oi mm. — Nav. (VanheurcMa?) styriaca Grun. V. H. Syn. Pl. XVII f. 7, 8. 



Fresh water? 



I have not seen this species, which has the appearance of a small F. rJiomhoides. 



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

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

 slightly radiate in the middle, transverse at the ends. Frustules enclo.sed in unbranched gelatinous 

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

 LVI f. 351. Grun. Bänka D. II f 15. Nav. dirhynchus Donk. B. D. Pl. V f . 3 (1871) Ehb.? 

 Kiitz? VanheurcMa vulgaris V. H. Syn. p. 112 Pl. XVII f. 6. 



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

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



Var. asynimetrica Cl. — 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. Strife 22 to 30 in 0,oi mm., somewhat radiate in tlie middle and closer at 

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

 Pl. V f. 29. 



Braekish 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, le; 

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

 0,0 1 mm.; longitudinal strise 20 to 25 in 0,oi mm. — Å''ap. rhomboides Ehb. Am. III: i f. 15? 

 W. Sm. b. D. i Pl. XVI f. 129. Grun. Bänka D. Pl. II f. 14. Vanhenrcläa rhomh. Breb. Ann. 

 Soc. phyto. et micr. de Belgique Vol. I p. 204 (1868). V. H. Syn. p. 112 Pl. 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 ooarse longitudinal furrows. — N. lineolata 

 Ehb. Am. Pl. I: s f. 4 a? M. G. Pl. XVI: i f. 3 etc. 



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



Var. oregonica Cl. — V. narrow. L. 0,i ; B. O.ois mm. Transverse strise 30, longitudinal 

 25 in 0,0 1 mm. 



Fresh water: Oregon, fossil! 



