336 DIMEREGRAMMA. 



ANALYSIS OF SPECIES. 

 ' Valve more or less broadly lanceolate ; pseudo-raphe lanceolate . . D. minor. 



Valve linear f 



or narrowly Valve not inflated at the median portion ; puncta tine . D. fulvum. 



lanceolate ; J 

 [ pseudo-raphe "1 



linear, Valve somewhat inflated in the middle ; puncta robust . D. marinum 



narrow (, 



D. minor (Greg.) Ralfs. (Greg. Diat. of Clyde, p. 23, pi. 2, f. 

 35, sub Denticula; H.V.H. Atl., pi. 36, f. 10 and iifl*), plate 10, fig. 392. 



Valve lanceolate, with apices obtuse, smooth ; pseudo-raphe very gently 

 dilated towards the median portion; striae 10 in 1 c.d.m. formed of well 

 marked puncta, rather distant, not forming longitudinal lines. Frustules 

 quadrangular, attenuate underneath the apices, which are obtuse-truncate. 

 Length, 3 to 4 c.d.m. 



Marine. Blankenberghe, Ostend. Scotland (Lamlash Bay and Loch Fyne, Greg. ! Cumbrae, 

 sand washings, Baxter Coll., No. 2478. Ireland (O'Meara). 



var. nana. (Denticula nana Gre*., Diat. of Clyde, p. 23, pi. 2, f. 34; 

 H.V.H. Atl., pi. 36, f. wb, 12, and 13*), plate 11, fig. 393. 



Valve inflated at the median portion, with apices abruptly attenuate; 

 stria? 14 in 1 c.d.m. ; girdle face as in the type-form, but shorter. 

 Length, 1 to 2 c.d.m. 



Marine. Blankenberghe, Ostend. Mixed with the preceding. England (Stolt.), 

 Scotland. 



D. fulvum (Greg. !) Ralfs. (in Pritch. Inf., p. 790; Denticula 

 fulva Greg. ! ; H.V.H. Atl, pi. 36, f. 7*), plate 30, fig. 849. 



Valve very narrowly linear, with apices gently capitate, rounded ; striae 

 about to in 1 c.d.m., distinctly granular. Girdle face rectangular, narrow. 

 Length, 4 to 7 c.d.m. 

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



D. marinum (Greg. !) Ralfs. (in Pritch. Inf., p. 790; Denticula 

 marina Greg. ! ; H.V.H. Atl., pi. 36, f. 9*), plate 30, fig. 849 bis. 



Valves lanceolate, linear, gently inflated at the median portion, with apices 

 obtuse, rounded. Raphe rather broad, lanceolate, somewhat dilated at the 

 median portion, terminated by rounded smooth spaces. Stria;, 4 in 1 c.d.m., 

 formed of very coarse puncta. Girdle face rectangular, very narrow, some- 

 what attenuate near the apices. Length, 8 to n c.d.m. 



Marine. English Channel (Temp, and Perag., No. no). Scotland (Lamlash Bay, Greg. !) 

 Ireland (O'Meara). 



