104 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



A. robusta is nearly related to A. Proteus and difFers principally by the coarse striee and 

 larger size. A. ohlonga GtREG. (D. of Clyde p. 515 Pl. XIII f. 78) seems to be a form of A. robusta, 

 bnt I liave never met with any perfectly similar form. 



10. A. javanica A. S. (1875). — Frustule rectangular, about three times longer than broad. 

 L. 0,045 to 0,06; B. 0,oi7 to 0, 02 mm. Zone not complex. Axial area narrow, dilated on the 

 dorsal side around the central nodule. Keel or longitudinal line on the dorsal side very distinct. 

 StriiS 12 in 0, 01 mm. composed of elongated distant puncta. Ventral side striate, except in the 

 middle. Strise 12 in 0, 01 mm. curved, composed of some few elongated, large puncta or crossed by 

 an nndnlating narrow line. — Atl. XXVII f. 27, 30 to 33. 



Marine: Java! 



This form is very nearly akin to A. arenicola, of which it may be a variety. 



11. A. arenicola G-run. (1882). — Frustule nearly rectanguJar, three times longer than 

 broad. L. 0,038 to 0, 07; B. 0, 017 to 0, 021 mm. Valve in breadth 0, 01 mm., linear, with broad, 

 unilaterally rounded ends. Median line slightly biarcuate, distaut from the ventral margin. Axial 

 area indistinct on the dorsal side. Central area none or orbicular. Dorsal side with 10 to 14 

 coarsely punctate, not interrupted, strise in 0, 01 mm. Longitudinal line indistinct. Ventral side 

 broad, with radiate, coarsely punctate strise, sometimes crossed by a narrow, blank band. — A. 

 marina rar. arenicola Grun. in Cl. M. D. N:o 310. A. marina Pritch Inf. Pl. V f. 59? A. arenic. 

 Icon. n. Pl. IV f. 19, 20. 



Marine: Coasts of England and Belgium! China (Beby CoU.)! 



Var. major Cl. — V. in L. 0,i; in B. 0, 026 mm. Strise 8 to 9 in 0, 01 mm. composed of 

 large, distant puncta. — A. robusta A. S. Atl. XXVII f. 39 to 41. A. Lima Pant. Ill Pl. XXTII 

 f. 347 (1893). 



Brackish water: Baltic! 



Var. oculata Cl. — Frustule in L. 0,07; in B. 0,o36 mm. Central area on the dorsal side 

 large, rounded. Strise 11 in 0, 01 mm. composed of large, distant puncta. — Pl. IV f. 21. 



Marine: Sebastopol! 



Var. subcequalis Cl. — Frustule linear elliptical. L. 0,07.5; B. 0,o32 mm. Median line bi- 

 arcuate, very distant from the ventral margin, so that the ventral side is almost as broad as the 

 dorsal. Dorsal side with 10 strise in 0,oi mm., composed of large puncta, 10 in 0,oi mm. Ventral 

 side entirely covered with coarsely punctate strise. — Pl. IV f. 22. 



Marine: China (Deby CoU.)! 



12. A. ovalis KtJTZ (1833). — Frustule broadly elliptical, with truncate ends. L. 0,oi to 

 0,06; B. 0,0045 to 0,033 mm. Valve lunate with subaeute ends. Median line slightly biarcuate. 

 Axial and central areas on the dorsal side indistinct or distinct. Dorsal side twice as broad as 

 the ventral. Ventral side with a row of short strise. Dorsal part with 10 to Ifi strise in 0,01 

 mm. Strise punctate, not interrupted, or crossed by a somewhat irregular blank band. 



Forma iypicu. Frustule in L. 0, 04 5 to 0,o6; B. 0, 024 to 0,1133 mm. No axial and central 

 area, no longitudinal band on the dorsal side. Strise, 10 to 11 in 0,01 mm. composed of distinct 

 puncta (al)out 9 in 0,oi mm.). — A. orali.^^ KuTZ Syn. f. 5, (5. Bac. p. 107. V. B. Syn. p. 59 

 Pl. I f. 1. H. L. Sm. Types N:o 40. 



Fresli water: Sweden! England! France! (lermany! Switzerland (Brun), Baltic (Gulf of 

 Bothnia!) Australia, Lake Muir! 



Var. gracilis Ehb. (1843). — As the type, but smaller. L. 0,027; B. 0,01 mm. Strise about 

 12 in 0,01 mm. — A. gracilis Ehb. Ain. p. 122 Pl. 111: 1 f. 43. A. ovalis var. </r. V. H. Syn. p. 59 

 Pl. T f. 3. A. S. Atl.' XXVI f. 101. 



Fresh water: Belgium (V. H.), Harz (Atl.). 



Vai-. libyra Enji. (1840). V. Innate. L. 0,05n to 0,os; B. 0,o 1 1 fo 0,017 mm. Median line 

 slightly biarcuate. Centi'ai ai'pa distinct on the dorsal side, frequently uniting with an irregular, 



