BG 



Mer., but the girdlc lacc is vcry differcnt; the septa of the lattcr 

 species are very deep, and the lower apex of the valve is inflated. 

 Thy are not related to one another. 



3ó. L. rostrata Mer. [fig. 2Ó]. 



Valve narrow, cuneate, gradually attenuated towards the lower 

 end, with usually straight margins, abruptly attenuated at the upper 

 end forming a long narrow rostrum, inferior apex narrow, acute. 

 Pseudoraphe distinct, striae usually distinct at an ordinary magni- 

 fying power, 13-14 in 001 mm. in the middle part. Girdle face nar- 

 row, linear in its upper '/, or '/, (sometimes even more), with an- 

 gles subacute, margins rather strong, becoming thin at the upper 

 part Septa very deep (0.012 mm.), thin, moderatly arcuate, parallel 

 above the septal puncta, the latter round, very distinct. Endochrome 

 granular. Length o.oyS-o.nó mm., breadth of the girdle face 0.0 io5- 

 0.019 mm., breadth of the valve 0.0048-0.0072 mm. 



Locality: Black sea (lalta, Sebastopol), common! Mediterranean 

 (Villefranche), not rare! Adriatic (Pola, Ancona), rather rare! Cali- 

 fornia (San Fedro), rare (type.^). 



The form of the valve is nearly the same as in L. proboscidea 

 Mer., but the latter is much more delicate, its size smaller, the 

 striae much finer, the girdle face cuneate. Nevertheless there can 

 be but little doubt that this species has originated directly from L. 

 rostrata. 



37. L. semiasymmetrica Mer. [fig. 27J. 



Valve narrow, davate, partly symmetrical, partly more or less 

 asymmetrical, inflated in the upper third, somewhat abruptly atte- 

 nuated in the midle or below, slightly attenuated towards the supe- 

 rior end which is broader than the inferior and more or less pro- 

 duced with apex rounded. lower end narrow; in the asymmetrical 

 type the valve is more or less arcuate, abruptly attenuated in its 

 middle part on one side (the concave one) only. f^seudoraphe inde- 

 finite, striae very fine. Girdle f^ice narrow, cuneate, with upper an- 



