134 



p. T. CLEVK, SYNOPtSI.S OF THE NAVICULOID DIATOMS. 



5. A. (Iclpliinea (Bail. 1S(U?) A. S. Atl. (1870). - Frustule silicious, broadly elliptic-rec- 

 tangular, frecpieiitly gibbous in the middle. L. 0,o76 to 0,12; B. (),05 to (),()68 mm. Valve linear 

 to lunate, with obliquely rounded ends. Central nodule dilated to a stauro.s. Terminal fissures 

 deep. Strife 27 to 28 in (),oi mm., on the dorsal side parallel, on the ventral divergent towards 

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



Fresh water: Demerara River! 



Var. minor Cl. — V. in L. O.oe; B. 0,(ii'j mm. Strife 24 in O.oi mm. — A. S. Atl. XL f. 25. 



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



A^ar. jamalinensis Cl. a. Grun. (188()). — V. more linear, with gibbous middle. L. 0,048 to 

 0,0.57; B. ((,01 to 0,011 mm. Striie very fine. — A. ocellafa i:ar. janial. A. I), p. 24 PI. I f. (1. 

 A. S. Atl. XL f. 24? 



Brackish water: Sea of Kara! Pensacola (Atl.)V 



It is difficult to find any specific distinction between this species and A. ocellafn. Yet they 

 cannot lie regarded as the same species. A. ocellafa is thinner, has somewhat coarser stria', and 

 less deeply impressed terininal fissures. Moreover A. dclpliinca is a freshwater form and A. 

 occllnta nuirine. 



(i. A. Berggrciiii Cl. (1878). — Frustule silicious, suhrectangnlar with rounded ends. 

 L. O,ot;,'i; B. 0.02.5 mm. Median line with distant median pores; its terminal fissures deep and 

 flexuose. Central nodule not dilated into a stauros. Dorsal strife parallel, 17inO,oi mm., ventral 

 strife divergent towards the median line. — Cl. a. M. D. N:o 90. Cl. N. R. I), p. 4 PI. I f. ;i 

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



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



This remarkable species is evidently akin to .4. ddpliinea, although its central nodule is 

 not dilated to a stauros. 



7. A. hiaiis Flogel (1878). — Frustule elliptical, in the middle slightly constricted, with 

 truncate ends. L. 0,045; B. 0,015 mm. V. narrow with slightly refiexed ends. Central nodule a 

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



Marine: Knarrhoi, Kattegat (Flogel). 



Subgenus Cymbamphora. 



Valve narrow elongated, semilanceolate, gradually tapering from 

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

 mate to the ventral margin. Strise not crossed by longitudinal lines. 

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

 car. rentricosa have a chromatophore-plate along the ventral side of the 

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

 deeply constricted in the middle. 



This subgenus, in which the valves have a considerable likeness 



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



A. angusta var. vcntricosa many of the re])uted species differ in nothing but the number of strife, 



!nts; '■'"' '"' 



magnified. 



with cell-contents; (iOO times • n ,-, , i i j. -j- i i. • j." 



Size ot the valve, and such trining characteristics. 



Artificial Icij of species 



i Striae very fine 20 or more in O.oi mm 2. 



\ — coarser less than 20 in 0,oi mm 3. 



{ Frustule short, narrow elliptical A. cymbelloides Grun. 



\ — very elongated, linear .^1. arcta A. S. 



