143 



straight, somewhat divcrgent ncar the upper margin, septal puncta 

 quite marginai, sccondary puncta (') absent. Length 0.025Ó-0.074 mm., 

 breadth of the girdle face 0,01 43-0. 02ÓÒ mm., brcadth of the valve 

 0.008Ó-0.01 19 mm. (average o.oio5 mm.). 



Locality: Adriatic sea (Fiume), common. 



Differs from L. anglica, which it resembles in its girdle face, 

 by the strongly davate form of the valves and their greater breadth. 

 It is also nearly allied to L. oviiliun Mer. wich, howewer, is smaller 

 and has ovoid valves. 



2. L. araphidiea Mer. 



Valve narrow, cuneate, gradually tapering from the summit to 

 the lovver end, maximal breadth near the very upper end, which ter- 

 minates in a short rostrum, lower end rounded. f^seudoraphe absent. 

 Striae delicate but distinct, 12 14 in 0.01 mm. at the lower end, 

 i3-i5 in the middle, i5-i7 near the upper end, parallel, strongly 

 radiate at the summit. Septa not deep (about 0.014 mm.). Lenght 

 0.290-0.345 mm., breadth of the valve o.020-o.o3o mm., at the lower 

 end 0.00S6-0.01 14 mm. 



Locality: Sumatra! New Guinea (Tami Islands), rare. 



Remarkable for the absencc of a pseudoraphe, of vvhich there is 

 not the slightest trace. 



3. L. biplacata Mer. [fig. 2]. 



Valve moderatly broad, elongated ovoid, gradually attenuated to- 

 wards the interior end, with straight margins, superior apex roun- 

 ded; inferior acute. Pseudoraphe and striae very fine. Girdle face 

 cuneate, narrow, with inferior apex broad and superior angles acute. 

 Septa supcrficial (.-). Endochromc composed of two elongated plates 

 resting on each of the valves, with a large elaeoplast bclonging 



(V) I cali «secondary puncta» the (usually two) puncta situateci between the 

 septa at the upper margin of the frustule. 



