102 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DI ATOMS. 



1. A. beliriugensis Cl. N. Sp. — Frustule ellixitical, with truncate ends. L. 0,028; E. 0,oi4 

 mm. V. lunate, acute. L. 0,028; B. 0,oo6 mm. Median line nearly straight. Axial area of the 

 dorsal side broad. Ventral side not striate, very narrow. Dorsal strise 15 to 16 in 0,oi mm. not 

 crossed by a longitudinal line. — Pl. III f. 34, 35. 



Marine: Beliring Island! 



This small species seems to connect this group with the Cymbamphora. 



2. A. Ovum Cl. N. Sp. — Frustule broadly elliptical, very convex. L. 0,o4; B. 0,025 mm. 

 Median line nearly straight, approximate to the ventral margin. Axial area on the dorsal side 

 not distinct. Striise on the dorsal side 10 to 11 in 0,oi mm. composed of obscure granules and 

 not crossed by a longitudinal line. Ventral side narrow, structureless. — A. S. Atl. XXVI f. 40 

 (without name). Icon. n. Pl. IV f. 12. 



Marine: Balearic Islands! Java (Atl.). 



3. A. dubia (Greg. 1857?) A. S. (1875). — Frustule in outline elliptical. L. 0,04 to O.os; 

 B. 0,016 to 0,02 mm. Zone very narrow. V. angularly bent along a line combining the ends, so 

 that it, if seem from the end, appears composed of two laminee in an angle of about 60°. Outline 

 of the valve lunate, with arcuate exteriör, straight interiör margins and acute ends. Median line 

 straight, approximate to the ventral margin. Axial area moderately broad on the dorsal side of 

 the median line. Ventral part of the valve linear, narrow, without strige and longitudinal line. 

 Dorsal side strongly transversely striate, especially on the exteriör part. Strise 10 in 0,oi mm. 

 coarsely punctate; pimeta 12 in 0,oi mm. — D. of Clyde p. 514 Pl. XIII f. 76? A. S. Atl. XXVII 

 f. 20 to 26. Icon. n. Pl. IV f. 5, 6. 



Marine: Coasts of Norway! Balearic Islands! Barcelona! Adriatic! Campeachy Bay (Atl.), 

 Singapore (Atl.), Java! 



A. dubia of Grbgory seems to be some species of Amphora in the state of division, scarcely 

 the very characteric and isolated species, figured in Atlas. The form of the valve is generally 

 difficult to make ont, but I succeded with the aid of slides, mounted, by Mr Thum in which the 

 valves were placed on their extremities. They presented themselves like segments of an orange. 

 There is no species akin to A. dubia. 



4. A. valida Perag. (1888). — Frustule broadly elliptical, with rounded ends. L. 0,o7 to 

 0,08 mm. Valve broadly lunate. Median line approximate to the ventral margin. Axial area on 

 the dorsal side indistinct. Ventral side not striate. Dorsal side with 5 to 6 coarsely punctate 

 stritB in 0,oi mm. — D. Villef. p. 40 Pl. III f. 25. 



Marine: Villefranche, Medit. (Perag.). 



This species, unknown to me, has the form of A. Ovum bvit is much larger. 



5. A. Weinekii Jan. (1876). — Fimstule rectangular, with parallel margin.s. L. 0,ob; 

 B. O, o 1:5 mm. Valve linear, with gibbous ends. Median line straight. Axial area narrow, on the 

 dorsal side moderately broad, with some few obli(]ue stritie at the ends. Dorsal part with about 

 14 strite in 0,01 mm. — A. S. Atl. XXXIX f. 20. 



Marine ? 



This species, which I know only from the A. S. Atl., seems to be very characteristic and 

 rerjuires a more complete examination. 



6. A. Piisio Cl. — Frustule in outline l)roadly elliptical, with truncate ends. L. U.oa.r, to 

 0,1)27; B. 0,1117 nim. Median line strongly biarcuate. Central ntidule large. Axial and central 

 areas not distinct. Dorsal and ventral side with strong stria^, about 14 in 0, 01 mm., not inter- 

 rupted and not distinctly pnnctate. — Pl. III f. 40. 



Brackish water, marine: Coast of Sweden (Cl. M. 1). N:o 157j; Balearic Islands! Hilo, Sand- 

 wich Islands (in almost fresh water). 



