K0N6L. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 113 



akin to it. A. elongata Gres. (D. of Clyde p. 521 Pl. XIII f. 84) seems to be an elongated 

 variety of this species, whicli is nearly related to the following. 



15. A. Graeflii (Grun. 1875) Cl. — Frustule elliptical to rectangular, with broad, truncate 

 ends. L. 0,i; B. O, os mm. Zone with about 2 divisions in 0,oi mm. striate; strise 17 in 0,oi mm. 

 V. lunate, with almost straight ventral margin and not protracted ends. L. 0,i to 0,i3; B. 0,oi3 

 to 0,025 mm. Median line biarcuate. Axial area more or less broad on the dorsal side. Strite 11 

 to 14 in 0,01 mm., not distinctly punctate, and crossed by a conspicons, narrow blank line. Ventral 

 side structureless or with a row of faint and short strife. No distinct longitudinal line. — A. 

 GrceffiÅ var. A. S. Atl. XXV f. 40. A. truncata? Atl. XXVIII f. 5? A. Debyi Leud. Fortm. D. 

 de la Malaisie p. 10 Pl. I f . 4 (1892)? 



Marine: Gulf of Naples (Brun CoU.)! Zanzibar (Atl.), Sumatra (Deby Coll.)! China! Gala- 

 pagos Islands! 



A. Grceffii Grun. in A. S. Atl. is to judge from the figures the same species as A. Grevil- 

 leana. At least I am not able to discover any distinctive characteristics. I understand A. Grmffii 

 to represent a form, nearly akin to A. Grevilleana but with closer, not distinctly punctate 

 striee, and not protracted ends. The zones appear to differ in the divisions, which in A. Grceffii 

 are contiguous, but in A. Grevilleana are separated by an intermediate, blank, longitudinal band. 

 This requires further investigation. 



Var. staurophora Cl. — Central nodule transversely dilated to a short stauros. 



Marine: Gulf of Naples (Brun Coll.)! 



16. A. Grevilleana Greg. (1857). — Frustule more or less rectangular, with truncate ends. 

 L. 0,1 to 0,16; B. 0,035 to 0,i mm. Zone with about 3 divisions in 0,oi mm. transversely striate ; 

 strise 6 to 17 in 0,oi mm. V. with arcuate dorsal margin and more or less produced ends. L. 0,io 

 to 0,22; B. 0,02 to 0,03 mm. Median line biarcuate. Axial area more or less broad on the dorsal 

 side. Dorsal side with 6 to 10 strise in 0, 01 mm. Strise coarsely punctate, crossed by a distinct 

 longitudinal line or keel. Ventral side structureless, with a strong longitudinal line. — T. M. S. 

 V. p. 73 Pl. I f. 36. D. of Clyde p. 522 Pl. XIII f. 89. A. S. Atl. XXV f. 41. A. sulcata Greg. 

 D. of Clyde Pl. XIII f. 92? A. complexa Greg. 1. c. f. 90. A. fasciata Greg. 1. c. f. 91. A. Grceffii 

 Grun. A. S. Atl. XXV f. 42 (1875). A. Grev. var. prominens Gkun. A. S. Atl. XXV f. 43, 44. 

 Var. campecMana Grun. 1. c. f. 45. A. (Grevill. var.?) sepulta Pant. I p. 22 Pl. XXIV f. 223 

 (1886). A. sumatrensis Leud. Fortm. D. de la Malaisie p. 10 Pl. I f . 5 (1892)? 



Marine: Spitsbergen (small form L. O.i mm. Striae 12 on the valve, 17 on the zone in 0,oi 

 mm.)! North Sea! Guernsey! Morocco! Gulf of Naples! China! Magelians Strait! S:ta Monica 

 Calif., foss. (Deby CoU.)! Galapagos Islands! Campeachy Bay (Atl.). 



A. Grevilleana is a somewhat variable species, closely connected with A. Grceffii, from which 

 it is distinguished by larger size, more prominent ends and the coarsely punctate strise. On larger 

 specimens the latter seem under high power to be costate and alternate with double rows of puncta 

 (about 9 in 0, 01 mm.). 



Var. contracta Cl. — V. with straight ventral, and in the middle deeply sinuose dorsal 

 margin. Ends rostrate-capitate. L. 0,085 to 0,125; B. 0, 02 to 0,028 mm. Median line almost 

 straight. Axial area moderately wide on the dorsal side. Striai 8 in O, o 1 mm., costate and alter- 

 nating with double rows of puncta, 13 in 0, 01 mm. Keel across the strife strong. Ventral side 

 narrow. — A. S. Atl. Pl. XL f. 33. 



Marine: Barcelona! Grip, Norway (Atl.). 



17. A. proboscidea (Greg. 1857?) Cl. — Frustule elliptical, with truncate ends. L. 0,o65 

 to 0,07; B. 0,034 mm. Zone with 3 sharply defined divisions in 0,oi mm., transversely striate; 

 strite about 10 in 0,oi mm. V. with rostrate and incurved ends. Median line biarcuate. Axial 



K. Sy. Vet. Akad. Handl. Band 27. N:o 3. 15 



