L34 



P. T. CLEVK, SYNOPSIS OF THE NAVICULOID DIATOMS. 



5. A. delplihiea (Bail. 1861?) A. S. Atl. (1876). — Frustule silicious, broadly elliptic-rec- 

 tangular, frequently gibbous in the middle. L. 0,o7 6 to 0,12; B. 0,05 to 0,068 mm. Valve linear 

 to lunate, with obliquely rounded ends. Central nodnle dilated to a stauros. Terminal fissures 

 deep. StricE 27 to 28 in 0, 01 mm.,, on the dorsal side parallel, on the ventral divergent towards 

 the median line. — Bost. Jour. Nat'. Hist. VII Pl. I f. 1 (fide H. L. Sm.). A. S. Atl. XL f. 26, 27. 



Fresh water: Demerara River! 



Var. minor Cl. — V. in L. 0,o6; B. 0,1112 mm. Stria; 24 in 0,oi mm. — A. S. Atl. XL f. 25. 



Fresh water: North America, Crane Pond! Demerara River! 



Var. jamalinensis Cl. a. GtRUN. (1880). — V. more linear, with gibbous middle. L. 0, 04 8 to 

 0,057; B. 0,01 to 0,011 mm. StriiE very iine. — A. ocellata var. jamal. A. D. p. 24 Pl. I f. 6. 

 A. S. Atl. XL f. 24? 



Brackish water: Sea of Kära! Pensacola (Atl.)? 



It is difiicult to find any specific distinction between this species and A. ocellata. Yet they 

 cannot be regarded as the same species. A. ocellata is thinner, has somewhat coarser stritT?, and 

 less deeply impressed terminal fissures. Moreover A. delphinea is a freshwater form and A. 

 ocellata marine. 



6. A. Berggrenii Cl. (1878). — Frustule silicious, subrectangular with rounded ends. 

 L. 0, 6. '5; B. 0,0 2 5 mm. Median line with distant median pores; its terminal fissures deep and 

 flexuose. Central nodule not dilated into a stauros. Dorsal stria3 parallel, 17 in 0, 01 mm., ventral 

 strise divergent towards the median line. — Cl. a. M. D. N:o 90. Cl. N. R. D. p. 4 Pl. I f . 3 

 (1881). H. L. Sm. T. N:o 610. 



Fresh water: ISTew Zealand, Arthur's Pass, foss. ! 



This remarkable species is evidently akiii to A. clelphinea, although its central nodule. is 

 not dilated to a stauros. 



7. A. hiaiis Flögel (1873). — Frustule elliptical, in the middle slightly constricted, with 

 truncate ends. L. 0,045; B. 0,oi5 mm. V. narrow with sliglitly reflexed ends. Central nodule a 

 transverse stauros. Striie not seen. — Pommerania Exp. p. 88 f. 7. 



Marine: Knarrhöi, Kattegat (Flögel). 



A. nngn,sta var. tJcntricosa 



with cull-contents; HOO times 



niagnilioil. 



Subgenus Oymbamphora. 



Valve narrow elongated, semilanceolate, gradually tapering from 

 the middle to the acute or subacute ends. Median line straight, approxi- 

 mate to the ventral margin. Strije not crossed by longitudinal linés. 

 Connecting zone without divisions. — Living specimens of A. angusta 

 var. ventricosa have a chromatophore-plate along the ventral side of the 

 connecting zone. Another plate occurs on the dorsal side. Beth are 

 deeply constricted in the middle. 



This subgenus, in which the valves have a considerable likeness 

 to some Cymbellte, comprises marine forms only, so closely connected that 

 maiiy of the reputed species differ in notliing but the number of striiXJ, 

 size of the valve, and sitch triliing characteristics. 



Artificial Icey of species 



. I Stri£6 very fiiie 20 or more in 0,oi mm 2. 



\ — coar.sor less tluin 20 in 0,oi mm 3. 



„ f Frustule short, narrow elliptical A. cymbelloides Gbun. 



\ — very elongated, linear .fl. arcta A. S. 



