60 NAVICULE. 
free condition, and of N. Auklandica by De Frauenfeld in 
similar localities, certainly negatives this supposition. 
Hab. Marine. Warkworth, Northumberland, abundant 
in sand-gatherings, June and July 1869 (A. S. D.). 
Navicula simulans, Donkin. 
Amphiprora constricta, Ehren. Amer. 1844, p. 122, t. I. vi. fig. 28; 
- Kiitz. Bae. p. 107, t. xxix. fig. 34; Sm. Synop. vol. i. p. 44, 
pl. xv. fig. 126; Ralfs, in Prit. Inf. p. 922, pl. xii, fig. 1; 
Rabenh. Europ. Diat. p. 258, 
Plate IX. figs, 3a & 3 6. 
Frustule on M.V. oblong, with a sinuous constriction in the 
middle, extremities truncate, angles gently rounded. 
V. hyaline, lmear, with cuneate subacute extremi- 
ties; striz very fine, obscure (68 in ‘00l", Smith), 
transverse, reaching to the median line, much short- 
ened opposite the central nodule, so as to leave a 
transverse median blank space reaching near to the 
margin. 
Although this species has hitherto been described as an 
Amphiprora, it is wanting in the distinctive characters of 
this latter genus, between which and the Navicule it forms 
one of the connecting links. It is undoubtedly a Navi- 
cula, and its proper position in the present subsection, 
being allied to N. maxima, Greg. 
Hab. Salt water: frequent. Coast of Sussex (Prof. 
Smith); Newbiggin, Northumberland (4. S. D.) ; near 
Hull, common (Mr. Norman). 
Navicula maxima, Gregory. 
Navicula maxima, Greg. Quart. Micr. Journ, vol. iii. p. 41, pl. iv. fig. 19, 
and Trans. Micr. Soc. n. s. vol. iv. p. 89, pl. v. figs. 2, 2**. 
