34 



32. L. profundeseptata Mer. [fig. 23]. 



Valve moderatly broad, elongated ovoid, with somewhat convex 

 margins, abruptly attenuated in the lower Y^ which is produced, in- 

 ferior apex narrow, superior broadly rounded. Pseudoraphe rather 

 delicate, striae distinct with an ordinary magnifying power at the 

 inferior '/^ only, about i3-i4 in o.oi mm., becoming farther on in- 

 visible. Girdle face cuneate, moderatly broad, with upper angles well 

 rounded, margins moderatly strong. Septa excessi vely deep (o.oioS 

 mm.), almost straight and very thin below the septal puncta, diver- 

 gent and stronger above them ; septal puncta small, round, very dis- 

 tinct. Endochrome granular. Length 0.038-0.0475 mm., breadth of 

 the girdle face 0.018-0.025 mm., breadth of the valve o.oo855 mm. 



Locality: Mediterranean (Villefranche), very rare. 



This species has the deepest septa known ; in this respect as in 

 many others it resembles L. Monksiae and can be considered as a 

 mediterranean representative of a peculiar small groupe of Licmo- 

 phorae-Profundeseptatae. The secondary septal puncta are not ad- 

 joining the septa as in L. Monksiae. 



33. L. quadriplacata Mer. [fig. 24]. 



Valve very narrow, bacilliform or narrowly cuneate, rarely da- 

 vate, gradually attenuated towards the lower end, with straight or 

 nearly straight margins, inferior apex very narrow, acute, superior 

 part very slightly attenuated, superior apex broadly rounded or so- 

 mewhat truncate. Pseudoraphe indefinite, striae very fine. Girdle face 

 narrowly cuneate, with angles subacute; septa supcrficial, straight, 

 very fine, septal puncta small, strongly marginai, lindochrome com- 

 posed of four elongated plates resting by pairs on each of the val- 

 ves, separatcd transversally, with margins extending on the girdle 

 face. Forming small colonies of 1-4 not excceding 14 individuals on 

 moderatly elongated, structurless stipes, with dichotomic ramification. 

 Length 0.021-0.054 mm., breadth of the girdle face 0.007Ò-0.012 mm., 

 breadth of the valve 0.00285-0.0048 mm. 



