101 



Navicula firma, Kiitz. 



Navicula Jirma, Kiitz. Bacill. p. 92, t. XXI. fig. 10 ; Ralfs in Prit. Infs. p. 

 909; Donkin, Brit. Diat. p. 31, pi. V. fig. 7; Sm. Syn. Vol. I. p. 48, pi. XVI. fig. 

 138; O'Meara, Rep. on the Irish Diat. p. 366, pi. 31, fig. 26. 



Navicula ampJiigomphtts, Kutz. Bacill. p. 93, t. XXVIII. figs. 40 ^ncl 41 ; 

 Rabenh. Siissvv. Diat. p. 38, t. VI. fig. 47; Ralfs in Frit. Inf. p. 90S; Van Heurck, 

 pi. XIII. fig. 2; O'Meara. Rep. in the Irish Diat. p. 367, pi. 31, fig. 27. 



Navicttia Iridis, Ehr. 



Pinnularia amphigofuphus, Ehr. 



Valve large, linear lanceolate with obtuse extremities ; striae 

 punctuate, transverse, parallel, longitudinally crossed near the 

 margin; free space narrow and more or less inflated at central 

 nodule. (Plate XC fig. 15,) i7^^.— Fresh water. Clifton, New 

 Dorp. 



In consequence of being subject to considerable variation in 

 outline, the position of this species is in a state of great confu- 

 sion. Kutzing's typical form was found in the well known fossil 

 diatomaceous earth from Tanta Fiore in Italy ; as it occurs in 

 this deposit its outline is almost linear, with cuneate, obtuse or 

 sub-acute extremities. Ehrenberg, however, had elevated into a 

 species that form of it in which the linear margins and cuneate 

 extremities are most prominent, and into another spe(;:ies the 

 other variety, in which the middle of the valve is more tumid, 

 or elliptical; the former he named N. amphigonipJms, the latter 

 -A^. dilatata. Between these two forms, however, every degree of 

 gradation is observable; consequently both are synonymous 

 with Kutzing's type. — Donkin. 



Navicula trinodis, Sm., van inflata, Schultze, n. van 



Navicula trinodis, Sm. Syn, Vol. ii. p. 94, Kiitz. Bacill. p. 127 ; Ralfs in Prit. 



Inf. D. Sa.i • V^« TT^^nrol^ T^l -VT^r fi^c OT n IT K 



p. S94 ; Van Heurck, pi. XIV. figs. 31 a. 31 b. 



-"1. p. B94 ; Van Heurck, pi. XIV. figs. 31 a. 31 b. 



Valve with two constrictions and three nearly equal inflations; 

 extremities broadly rounded ; strise linear-punctate, parallel, not 

 reaching to the median line ; intermediate free space narrow ex- 

 cepting in the centre, where it is much expanded and shows a 

 slight granular structure. 



//a*^.— Fresh water, Clifton, in pond near the old town road, 

 scarce. (Plate XC. fig. 7.) 



Navicula 



A lie aescnption oi i\avicma irinoai^ lu uuc «ulw^.. ..--- 



"lention this species is very incomplete ; thus both Wm. Smith 



