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



28. A. exsecta Grun. (1875). — Frustnle in outline more or less rectangular to elliptical, 

 indented in the middle. L. (),o6 to 0,o6 5; B. O.022 to 0,o3 mm. Zone with numerous divisions, 

 about 5 in 0,01 mm., striate; strife 11 to 12 in 0,oi mm. Dorsal margin without limbus. V. with 

 arcuate dorsal and straight ventral margins, and somewhat rostrate, slightly incurved ends. Median 

 line straight, near the ventral margin. Longitudinal line on the dorsal side distinct. Central 

 nodule transversely dilated to the longitudinal line. Axial area broad. Strife 10 to 11 in 0,01 

 mm. composed of coarse puncta, about 11 in 0,oi mm., forming undulating, longitudinal rows. Ventral 

 side structureless. — A. S. Atl. XXVII f. 54, 55. Icon. n. PI. Ill f. 26 — 29. A. kamorthensis 

 var. minor A. S. Atl. XXV f. 81? 



Marine: Campeachy Bay (Atl.), China (Van Heurck and Deby Coll.)! 



A. milesiana Greg. (D. of Clyde p. 521 PI. XIII f. 83) seems to be a nearly related form, 

 with less distinctly indented centre. I have seen a specimen, somewhat resembling the fig. in 

 (jrveg. D. of Clyde, from the west-coast of Sweden, but the complex membrane prevented the exa- 

 mination of the valve. The fig. 13 PL XXXIX in A. S. Atl. seems to represent this form. 



29. A. Weissflogii A. S. (1875). — Frustule rectangular, indented in the middle, with 

 conspicuous and broad hyaline limbus. Zone complex, with about 4 divisions in 0,oi mm., coarsely 

 striate; stria* 8 in 0,oi mm. V. with arcuate dorsal and straight ventral margins, and more or 

 less rostrate-capitate ends. L. 0,i to 0,113; B. 0,oi4 mm. Median line near the ventral margin. 

 Longitudinal line distant from the median line. Central nodule incrassate and transversely dilated 

 towards the longitudinal line. Axial area narrow; central area triangular. Strife 8 in 0,01 mm. 

 coarsely punctate outside, with distant puncta inside, the longitudinal line. (Ventral side not 

 observed). — Atl. XXV f. 58. 



Marine: Baldjik, foss. (Van Heurck Coll.)! 



This species is no doubt nearly akin to A. exsecta, and the small form figured in A. S. Atl. 

 f. 59 appears to be more nearly connected with A. exsecta than with the type. A. kamorthensis 

 Grun. (Nov. p. 99 PI. I A f. 12; 1867) seems to be an allied species, of which I have not seen 

 specimens. 



30. A. cuiieata Cl. (1876). — Frustule elongated, truncate, constricted or indented in the 

 middle. L. 0,03 to 0,08; B. 0,oi3 mm. Zone with about 4 divisions in 0,oi mm., transversely 

 striate on the ventral side of the frustule (strife about 12 in 0,01 mm.) transversely costate on 

 the dorsal side (costfe 5 to 8 in 0,oi mm.). Hyaline limbus small, at the constriction of the valve, 

 frequently indistinct. V. narrow, with sinuose dorsal margin, arcuate in the middle, and subcapitate 

 ends. Central nodule incrassate, dilated to a stauros. Axial and central areas indistinct. Longi- 

 tudinal line on the back of the dorsal side. Strife 10 to 11 in 0,oi mm., coarsely punctate. 

 Ventral side narrow, structureless, with a longitudinal line. — A. S. Atl. XXXIX f. 29. Icon. n. 

 PI. Ill f. 23—25. A. hjrata Greg. D. of Clyde p. 520 PI. XIII f. 82 (1857)? A. S. Atl. XXVI 

 f. 2 (small form?). A. decora Castr. Voyage Challenger D. p. 18 PI. XXVII f. 14. 



Marine: Balearic Islands! Adriatic! Macassar Straits! Pensacola! 

 This species by its peculiar connecting zone suggests A. Peragalli. 



31. A. graiiulifera Cl. N. Sp. — Frustule in outline lanceolate, constricted in the middle. 

 Ends rostrate-truncate. L. 0,o-i to 0,047; B. 0,oi5 mm. Zone with about 4 divisions in 0,oi mm., 

 transversely costate, costfe about 7 in 0,oi mm. V. with arcuate dorsal and straight ventral 

 margins. Ends rostrate. L. 0,028 to 0,046; B. 0,007 to 0,oi mm. Median line straight, near the 

 ventral margin. Axial area indistinct; central area a short fascia on the dorsal side of the 

 nodule. Longitudinal line near the dorsal margin. Striae 10 in 0,oi mm.; inside the longitudinal 

 line resolved into large, distinct puncta. Ventral side narrow, linear, structureless. — PI. Ill 

 f. 32, 33. 



Marine: Java (Cl. M. D. N:o 147). 



