KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 89 



Forma minor Cl. — L. O.os to 0.04.';; B. 0,oi5 to 0,u23; at tlie constr. O.uis to 0, 02 mm. 

 Central nodule small. Trausverse costs' 11 in O.oi mm.; longitudinal 9 in 0,oi mm. 



Marine: Tahiti! Madaga-scar ! 



The f. minor may be the same as Nav. fiitilis A. S. Atl. XIII f. 17 from Zanzibar, btit 

 the furrows are not drawn as dilated around the nodnle. 



Var. moesta A. S. 1881. — V. slightly constricted. L. 0,09; B. 0,034; at the constr. 0,029 

 mm. Transverse costse 7 in 0,oi mm. — Nar. moesta A. S. Atl. LXIX f. 18, 19. 



Marine, fossil: Baltjik (Atl.). 



D. homhoides is very nearly akin to D. spJendicIa, from which it difters only in the furrows 

 whieh are slightly dilated around the nodule, a characteristic which seems to be variable. To judge 

 from specimens from Bory Ueposit in Hungary Nat\ andesitica Pant. (1889, II p. 42 Pl. XXVII 

 f. 390) seems to be somewhat corroded specimens of D. homioides with rather eloser costte. 



38. D. divergens A. S. (1875). — V. more or less constricted in the middle, with eUiptical 

 to tongue-shaped segments. L. O, oss to 0,045; B. 0,oi8 to 0,02; at the constr. 0,012 to 0, 013 mm. 

 Central nodule small, quadrate; its horns divergent at the basis, convergent at the ends. Furrows 

 Knear, broader around the central nodule, forming a lanceolate space. Transverse costte 11 in 

 0,01 mm., crossed on each side of the median line by about 5 longitudinal, slightly curved eostce. — 

 Nav. divergens A. S. Atl. XII f. 50, 51. 



Marine: Mediterranean Sea! 



Var. digrediens A. S. (1881). — V. less consti'icted. L. 0, 04; B. 0,019; at the constr. O.m: 

 mm. Transverse costse 13 in 0, 01 mm. Longitudinal costse less distinct. — Nav. digrediens A. S. 

 Atl. LXIX, f. 26, 27. 



Marine: Tahiti! Baltjik, foss.! 



39. D. Schmidtii Cl. N. Sp. — V. slightly constricted in the middle, with broad tongue- 

 shaped segments. L. 0, 027 to 0,075; B. 0, 011 to O, oss; at the constr. 0, 0105 to 0,027 mm. Central 

 nodule small, quadrate; its horns divergent in the middle. Furrows broader in the middle, 

 narrower at the ends, with faint traces of the costse. Transverse costse 8 to 9 in 0, 01 mm. crossed 

 on each side of the median line by 3 to 4 more or less undulating longitudinal costte. — A. S. 

 Atl. XII f 48; LXIX f. 23 (smaU, but typical). XIII f. 18, 19. — Icon. n. Pl. I f. 20, 21. 



Marine: Seychelles! Madagascar! Port Jackson! Tahiti! Galapagos Islands! 



This form is nearly akin to D. divergens. The lig. 18, 19 Pl. XIII in A. S. Atl. greatly 

 resembles larger specimens of D. Schmidtii, but has not divergent horns. Nav. vana A. S. Atl. 

 LXIX f. 30 is probably al so nearly related. 



40. D. cliineusis Cl. N. Sp. — V. slightly constricted, with broad, rounded ends. L. 0.055; 

 B. 0,02; at the constr. 0, 013 mm. Central nodnle elongated, quadrate; its horns parallel. Furrows 

 narrow, linear, not dilated in the middle. Costas 13 in 0,oi mm., alternatiug with single rows of 

 alveoli, about 16 in 0, 01 mm. — Pl. I f. 25. 



Marine: China (Thum). 



41. D. Gruiidleri A. S. (1873). — V. deeply constricted, very convex. Segments semi- 

 orbicular to broadly tongue-shaped, often of inequal size. L. 0,04; B. 0,02; at the constr. 0, 01 mm. 

 Central nodiile qi;adrate, large, with divergent horns. Furrows narrow, broader in the middle. 

 Ti-ansverse costse 7 in 0,oi mm., crossed by 2 to 4 longitudinal costEe, usually interrupted in the 

 middle of the valve. — Nav. Grimdl. A. S. Zeitschr. f. ges. Naturw. 1873 p. 407 Pl. VI f. 5, 6. 

 Atl. XII f. 35, 36. 



Marine: Balearic Islands! Bab-el-Mandeb ! Philppines! Atlantic coast of N. America! Para 

 River (A. S.). 



K. Vet. Akad. Handl. Band 36. N:o 2. 12 



