OMPHALOPSIS. 



335 



Gl. distans (Greg.) Grun. (H.v.H. Atl., pi. 36, f. 15, 16*- 



Denticuia distans Greg. ! Diat. of Clyde, p. 23, pi. 2, f. 36), plate 30, 

 fig. 848. 



Valves broadly lanceolate, with apices obtuse rounded, bearing on the 

 margins a row of beads (or short costae?), very coarse, 5 or 6 in 1 c.d.m.; 

 central nodule coarse, indistinct, terminal smooth spaces round, very large. 

 Girdle face quadrangular, slightly attenuated between the two smooth apices. 

 Length, 3 to 6 c.d.m. 



Marine. Coast of Scotland (Lamlash Bay, Greg. !), Ireland, Sweden. 



/TTt 



GENUS 56. OMPHALOPSIS GREV., 1863. 



Valve cruciform, with apices 

 rounded, obtuse, smooth, separated 

 from the rest of the valve by a 

 transverse diaphragm. Pseudo-raphe 

 narrow, enlarged round the central 

 nodule, which is very coarse. Girdle 

 face rectangular, with rounded angles. 

 Frustules united into a filament. 



\^=JJ 



Fig. 92. 

 Omphalopsis Australis lirev. 



a. Valve view. b. Girdle view. 



This genus consists of a single species 

 O. Australis, represented in the text. 

 The valve is sometimes elongated, some- 

 times short, thick-set ; the striae, about 

 4 in i c.d.m., are very distinct and formed 

 of small distinct beads. 



Marine. Seychelles Isles (Coll. Weissf. !). Dred- 

 ging off Woodlark Island (Roberts). 



Fig- 93- 



Dimercgramma 



fulvum. 



a. Girdle view. 



b. Valve view. 



GENUS 57. DIMEREGRAMMA 

 RALFS., i860. 



Valve with striae interrupted by a pseudo-raphe, 

 broad and dilated at the median portion, with apices 

 smooth. Without a central transverse smooth space. 

 Frustules united in filaments. 



This genus, in fact, only differs from Glyphodesmis by the 

 absence of a central pseudo-nodule. The genus Dimere- 

 gtamma includes about a dozen species, three of which 

 belong to our shores. 



