KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. Ht3 



central; its terminal fissures laterally expanded. Axial area indistinct; central area rounded- 

 quadrate. Alveoli disposed in oblique and transverse rows, the latter curved and slightly radiate, 

 10 in 0,01 mm. — Nav. cleps. Donk. M. J In. s. p. 8 PL I f. 3. B. D. p. 63 PI. X f. 2. A. S. 

 Atl. XLVIII f. 7—8 (no name). 



Marine, aestuaries: Coasts of Scotland and England! Cape Horn (P. Petit). 



Var. scotica A. S. (1876). — Smaller, more linear. L. 0,085 to O.og; B. 0,oi5 mm. — Nav. 

 scotica A. S. Atl. XLVIII f. 9—11. Cl. M. D. N:o 303. 



Marine: Scotland! 



4. T. Debyi Letjd. Fortm. (1892). — V. linear-lanceolate, convex, gradually tapering towards 

 the obtuse ends. L. 0,i.'j to 0,3o; B. 0,025 to 0,04 mm. Axial area narrow linear, symmetrical; 

 central area orbicular. Alveoli disposed in oblique and transverse rows, the latter parallel, 8—9 

 in 0,01 mm. Longitudinal fine strise about 20 in 0,oi mm. — Nav. clepsydra A. S. Atl. XLVIII f. 39. 



Marine and brackish: Red Sea! Sumatra (G-rove Coll.)! Java (Kinker Coll.)! Singapore! China 

 (Penang Harbour Dr. Eae Coll.)! Australia (St. Vincent, Atl.)! 



Var. osculifera Cl. — Axial area unilateral; central area with a linear marking on both 

 sides of the central nodule. — Alloioneis Debyi Leud. Fortm. D. de la Malaisie p. 18 PI. II f. 5. 



There can be no doubt that T. Clepsydra and T. Debyi are distinct species. The fig. 38 in 

 A. S. Atl., (Nav. cleps. var.?) appears to be a variety of T. aspera, or perhaps a new species. 



.'). T. Johnsoninna G-rev. (1863). — V. elliptic-lanceolate, with obtuse or subrostrate ends. 

 L. 0,09 to 0,11; B. 0,033 to 0,03 7 mm. Axial area indistinct; central area, large, widened and 

 rounded outwards. Alveoli disposed in longitudinal and transverse rows; the former about 6 in 

 0,01 mm.; the latter radiate throughout, 8 — 10 in 0,oi mm. Longitudinal fine strise 25 in 0,oi 

 mm. — Nav. Johns. &rev. T. M. S. XI p. 17 PL I f. 8. Nav. Sieboldii Pant. Ill PL XX f. 293 

 (1893)? Track. Johns. Icon. n. PL III f. 38. 



Marine: Java (Deby Coll.)! Queensland (Grev.), Port Jackson! New Zealand (Grrev.), Japan, 

 Sendai Dept (Brun Coll.)! 



The valve is sometimes slightly asymmetrical, the median line being excentric. The central 

 area, rounded in typical specimens, is in some varieties dilated and truncate outwards, so that 

 T. Johnsoniana is closely connected with T. aspera. 



6. T. Brunii Cl. (1891). — V. broadly elliptical. L. O.oes; B. 0,034 mm. Axial area indi- 

 stinct; central area large, transverse, rounded outwards. Alveoli disposed in two to three longi- 

 tudinal rows along the median line, in oblique rows towards the margin. Transverse rows of 

 alveoli slightly radiate throughout, 9 (middle) to 12 (ends) in 0,oi mm. Longitudinal fine strise 

 about 26 in 0,oi mm. — Nav. Brunii Cl. in Brun D. especes n. p. 33 PL XVI f. 4. 



Marine: Japan (Brun Coll.)! China! 



This species has some resemblance to Nav. Ovum Faschale (A. S. Atl. PL VIII f. 56) also 

 from Japan, but this form, unknown to me, has not the large central area of T. Brunii. It seems, 

 nevertheless, probable that Nav. Ovum Paschale is a form of Trachyneis. 



7. T. Antillaruni Cl. (1878). — V. linear-lanceolate to linear-elliptical, with obtuse ends. 

 L. 0,12 to 0,17; B. 0,026 to 0,032 mm. Median line somewhat excentric. Axial area more or less 

 broad, irregularly linear and unilateral. Central area rounded, unilateral, on the opposite side of 

 the axial area. Alveoli disposed in longitudinal flexuose or irregularly oblique rows. Trans- 

 verse rows slightly radiate throughout 9 to 10 in 0,oi mm. — Alloioneis (Navicula?) Antillarum 

 Ol. West. Ind. D. p. 8 PL 11 f. 11. 



Marine and brackish: Campeachy Bay! West Indies! Florida! Bed Sea! Bab el Mandebi 

 Madagascar! Singapore! Java! Sumatra! China! 



K. Sv. Vet. Akad. Handl. Band 26. N:o 2. 25 



