102 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



1. A. behringensis Cl. N. Sp. — Frustule elliptical, with truncate ends. L. 0,028; B. 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 striae 15 to It) in 0,oi mm. not 

 crossed by a longitudinal line. — PI. Ill f. 34, 35. 



Marine: Behring Island! 



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



2. A. Ovum Cl. N. Sp. — Frustule broadly elliptical, very convex. L. 0,04; B. 0,025 mm. 

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

 not distinct. Strise 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. duMa (G-rbg. 1857?) A. S. (1875). — Frustule in ontline elliptical. L. 0,o4 to 0,o8; 

 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 laminse in an angle of about 60°. Outline 

 of the valve lunate, with arcuate exterior, straight interior 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 strise and longitudinal line. 

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

 coarsely punctate; ptincta 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 Gregory 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 out, 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. Talida Pbrag. (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 

 striiB in 0,01 mm. — D. Villef. p. 40 PL III f. 25. 



Marine: Villefranche, Medit. (Perag.). 



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



5. A. Welnekii Jan. (1876). — Frustule rectangular, with parallel margins. L. 0,06; 

 B. 0,013 mm. Valve linear, with gibbous ends. Median line straight. Axial area narrow, on the 

 dorsal side moderately broad, with some few oblique striae at the ends. Dorsal part with about 

 14 striae in 0,oi 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 

 requires a more complete examination. 



6. A. Pusio Cl. — Frustule in outline broadly elliptical, with truncate ends. L. 0,025 to 

 0,027; B. 0,017 mm. Median line strongly biarcuate. Central nodule large. Axial and central 

 areas not distinct. Dorsal and ventral side with strong strise, about 14 in 0,oi mm., not inter- 

 rupted and not distinctly punctate. — PL III f. 40. 



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

 wich Islands (in almost fresh water). 



