150 



Hawaii I bave found this varìety in a very pure condìtion, not mixed 

 with the type, while in Iwo others (lalta, Crimea and Catania, Sicily) 

 the type species is to be found ahnost pure (in Catania even quite 

 pure), thus showing that both forms are distinct. This variety is con- 

 nected by intermediate forms with L. Ehrenbergii. 



In the specimens from Hawaii the striae are a little closer(9-io 

 in o.oi mm. in the middle) than in those of the Black sea (8-9 in 

 the middle). This fact as well as the above described var. teìiui- 

 striaia of L. Ehrenhergii shows that the influence of climate (tem- 

 perature) on the number of striae is not always in conformity with 

 the theory advanced by Schumann and some others. 



16. L. bastata Mer. [fig. io). 



Valve narrow, davate, upper part rather abruptly broadened af- 

 fecting the shape ef the head of a spear, the summit conica!, with 

 acute apex, the lower part, corresponding to the spear-staff, very long 

 and narrow, gradually tapering towards the inferior end which is 

 acute. Pseudoraphe indefinite, striae very fine. Girdle face narrow. 

 cuneate, with angles subacute. Septa not deep, 0.0024-0.0033 mm., 

 very slightly arcuate, septal puncta small but very distinct, round. 

 Endochrome granular. Forming small colonies, usually of 2 (to 4) 

 individuai, often solitary, sessil or on very short stipes showing a 

 darker axial part. Length 0.081-0. 121 mm. (usually 0.057-0.067 mm ), 

 breadth of the girdle face 0.0095-0.022 mm., breadth of the valve 

 0.0076-0.0114 mm. (average o.oo855 mm.). 



Locality: Black sea! Mediterranean (Villefranche)! Adriatic (Pola)! 

 California (San Pedro), rare. P'requent but scarce ewerywhere. 



This species differs from L. dahìlis (Kùtz.) Grun. only by the 

 more or less rhombic, angular shape of the upper part of the valve 

 which in L. dehiìis is rather lanceolate, limited by more rounded 

 (not angular) outlines. This difference might appear to be a triOing 

 one, stili a very careful study of both forms has shown me that they 

 are two distinct species, or at least varieties. 



