103 



« * 



and Ralfs record the striae as obscure, and neither of them speaks 

 of a free median space. This want of information on the subject 

 led me to draw the Staten Island form at an amplification of 

 3000 diameters. 



Navicula Semen, Ehr. 



Navicula Semen, Kiitz. BacUl. p. 99. t. XXVIII. fig. 49 ; Rabenh. Siissw. 

 Diat. p. 33, t. V. fig. 2 ; Sm. Syn. Vol. I. p. 50. PL XVI. fig. 141 ; Ralfs. in 

 Prit. Inf. p. 900 ; Donkin p. 2i pi. III. fig. 8; O'Meara, Rep. on the Irish Diat. p. 

 413, pi. XXXIV. fig. 22; Schumann, Diat. d. H. Tatra p. 68. 



Valve linear elliptical; broad, with short shghtly constricted 



rounded extremities; striae reaching to the median line, costate, 



radiate towards the ends and convergent opposite the central 



nodule. 



Hah. — Fresh water, Clifton, frequent, (Plate XC. fig. 2.) 



Navicula borealis, Ehr. 



Nazdctda borealis, Kutz. Bacill- p. 96. t. XXVIII, fig. 68, 72; Van Heurclc, 

 Syu. p. 76, pi. VI. fig. 4; Ralfs in Prit. Inf. p. 907; O'Meara, Rep. on the Iri&l^ 

 Diat. p. 345, pi. XXX. fig. 14. 



Pinnidaria horcalis^ Rab. Siissw. Diat, p. 42, t. VI. fig. 19; Sm. Syn. Vol. n- 



p. 94. 



Valve linear elliptical with rounded ends ; costae very stout 

 and not reaching to the median line; intermediate free space 

 -broadj slightly inflated in the centre, 



i/^^._Fresh water, Clifton. (Plate XC. fig. 16.) 

 The Staten Island form of Navicula borealis is an exceedingly 

 large and beautiful one, being four inches in length when magni- 

 fied 1000 dia. The drawings in Van Heurck, Kiitzing and 

 O'Meara represent a much smaller diatom : the best of the three 

 authorities is that of VanHeurck, the others are imperfect in de- 

 tail. 



Navicula Liber, Sm. 



Navicula Liber, Sm. Syn. Vol. I. p. 48. pi. XVI. fig. 133 ; Ralfs. in Prit. Inf. 

 p. 907; Donkin. N. H. Br. Diat. p. 62, pi. IX. figs. 5 a, 5b ; Van Heurclc, Syn. 

 p. T04, pi. XII. fig. 36; O'Meara Rep. on the Irish Diat. p. 365, pi. XXXI. fig- 23. 



Valve linear with rounded ends; strict linear not reaching the 

 median Une, slightly radiate at apices; an intermediate free space. 



Hab. — Marine. South beach salt meadows at New Dorp. 

 Not frequent. (Plate XC. fig. 5.) 



