TABELLARIA. 



357 



T. flocculosa (Roth.) Kutz. (Baa, p. 127, pi. 17, f. 21 ; H.V.H. 



Atl., pi. 52, f. 10-12* ; Type No. 347), plate 11, fig. 478. 



Valve linear, with median inflation much greater than the terminal. 

 Pseudo-raphe very dilated in the median inflation. Striae 13 in 1 c.d.m., finely 

 punctate. Girdle face showing usually a considerable number (from 4 to S as 

 a mean) of false internal septa. Length, about 2 to 4 c.d.m. 



Fresh water. More common than the preceding. Antwerp (H.V.H. ). Louvain (P. Gaut. ). 

 Paliseul (Del. ). Ard. Lie'g. (De Wild.). England (Kitton, Norman, &c). Scotland (Dickie, 

 Arnott, Balfour, &c). Ireland (W. Sm., O'Meara), and throughout Europe. 



GENUS 69 TETRACYCLIC (RALFS, 1843) GRUN., 1862. 



Valve with costae transverse, not numerous. Girdle face showing 

 the margins of the valves and the internal septa, with apices somewhat 

 inflated (clavate). Frustules united in filaments. Endochrome 

 granular, sparse. 



ANALYSIS OF SPECIES. 



A. Frustules united by twos and threes ; valves elliptic without inflations . T. rupestris. 



B. Frustules united in long filaments ; valves inflated at the median portion. T. lacustris. 



A. Gomphogramma (A. Br.). 



T. rupestris (A. Braun) Grun. (Oest. Diat.,p. 412, pi. 7> f -37 : 



H.V.H. Atl., pi. 52, f. 13 and 14* ; Type No. 348 ; Gomphogramma rupestris 

 A. Br.), plate 11, fig. 489 a. 



Valve elliptic-lanceolate, showing 2 to 5 costae, 

 transverse, robust; stria; fine, about 18 in 1 c.d.m. 

 Girdle face generally showing two pairs of internal 

 septa. Frustules solitary or united by twos or 

 threes or more. Length, 75 to 2-5 c.d.m. 



Fresh water in mountainous regions. Very rare. Alle(Del.) 

 on damp rocks. England ? 



This diatom closely resembles Odontidium mesodon, but it is easily 

 differentiated from it, in the girdle face, by the presence of false septa. 



Fig. 107. 

 Tetracyclus rupestris. 



