KONGL. SV. VET, AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 83 



Var. Eudoxia A. S. (1875). — V. linear, with rounded ends. L. 0,07 to 0,085; B. 0,(ji7 to 

 0,022 mm. Costse 6 to 7 in 0,oi mm. Furrows narrower, than on the type. — Nac. nieditciraiica 

 A. S. N. S. D. PL II f. 10. Nav. Eudoxia A. S. Atl. VIII i. 40, LXX'f. 71. 



Marine: Morocco! Balearic Islands! Red Sea! Bab el mandeb! Madagascar! Ceylon! Gala- 

 pagos Islands! Monterey (Atl.). Fossil: Szakal, Hungary! 



Var. Eugenia A. S. (1875). — V. with subcuneate ends. L. 0,06; B. 0,oi7 mm. Costrti 7 

 to 8 in 0,01 mm. — Nav. Eugenia A. S. Atl. VIII f. 44. 



Marine: Ceylon (Leuduger Fortm.) Macassar Straits! Campeachy Bay (Atl.). 



There is, so far as I can see, no specific distinction between the above forms, which I regard 

 as belonging to D. contigua. They are perhaps all only smaller, and corroded, forms of D. gemmata'. 



15. D. circniniiodosa Bron. (1891). — V. very convex and thick, linear, with broad, rounded 

 ends. L. 0,i; B. 0,023 mm. Central nodule short and broad; its horns divergent at the nodule. 

 Furrows very broad. Costse 7 in 0,oi mm., continued across the furrows as rows of three large 

 puncta. — Nav. circumn. Brun. Esp. n. p. 33 PI. XVI f. 2. 



Marine: Japan, fossil (Brun Coll.)! 



16. D. Letourneuri Cl. N. Sp. — V. elongated, very slightly constricted in the middle, with 

 broad, rounded ends. L. 0,07; B. O.023; at the constr. 0,02. Central nodule elongated quadrate; its 

 horns nearly parallel. Furrows very broad. Costse 9 in 0,oi mm. almost parallel, continued 

 across the furrows, smooth. — PI. I f. 18. 



Marine: Columbo, Ceylon (Letourneur Coll.)! 



17. D. muscaeformis G-run. (1875). — V. gently constricted in the middle, with ciineate 

 ends. L. 0,o7 to 0,095; B. 0,03 to 0,04 at the constr. 0,024 to 0,037 mm. Central nodule quadrate, 

 with approximate, scarcely divergent horns. Furrows V2 to Vg as broad as the valve. Costse 4 

 to 7 in 0,0 1 mm., with faint continuations across the furrows. 



Var. placida A. S. L. 0,0 9 mm. Costte 4 to 4,5 in 0,oi mm. — Nav. placida A. S. Atl. 

 CLXXIV f. 2. 



Marine: Galapagos Islands! San Pedro Calif, fossil (Kinker Coll.)! Oamaru New Zealand, 

 fossil (Atl.). 



Var. genuina Cl. — Costse 7 in 0,oi mm. — Nav. muscoiform. A. S. Atl. XIII f. 42, 47. 



Marine: Campeachy Bay! Java! 



Var. constricta Grun. — Ends rounded. L. 0,o5 to O.oe; B. O.ois to 0,oi9 at the constr. 

 0,013 to 0,015 mm. Costfe 6 to 7 in 0,oi mm. — Nav. constricta Grun.? A. S. Atl. XII f. 65; 

 LXIX f. 42. 



Marine: Balearic Islands! Sansego (Atl.), Seychelles (Van Heurck Coll.)! Madagascar! Sum- 

 bava (Kinker Coll.)! Japan (Deby Coll.)! Leton Bank (Atl.). 



Var. pusilla Cl. — V. slightly constricted. L. 0,02; B. 0,oio mm. Costifi 9 in 0,oi mm. 



Marine: Galapagos Islands! 



This form is doubtful as a species, having very much the appearance of strongly corroded 

 valves of other species as D. Beyrichiana and allied forms. Grunow mentions a form from the 

 Caspian Sea in length 0,038 mm. and with 12 costte in 0,oi mm., which seems not to belong to 

 D. ntuscceformis. 



18. D. constricta Grun. (1860). — V. gently constricted in the middle, with subcuneate 

 ends. L. 0,06 to 0,i5; B. 0,023 to 0,03, at the constr. 0,o2 to 0,025 mm. Central nodule quadrate, 

 its horns parallel, approximate. Furrows very broad. Costfe 7 to 8 in 0,oi mm., very faint on 

 the furrows, radiate at the ends. — Nav. constricta Grun. Verb. 1860 p. 535 PL III f. 18 (according 

 to V. H. T 103). Nav. Musca Donk. B. D. p. 50 PL VII f. 6 (1873). .Var. Bonhinii A. S. N. S. 

 D. PL I f. 12 (1874); II i. 8. Atl. XII f. 63, 64. 



Marine: Finmark! North Sea! Balearic Islands! Ceylon! Florida! 



