3*6 SYNEDRA. 



S. fulgens (Kutz.) W. Sm. (S.B.D., i., P . 74 , pi. J2 , f. 103; 



H.V.H. Atl., pi. 43, f. i and 2*; Type No. 308), plate 10, fig. 436. 



Valve linear, narrow, with marginal sulci, often indistinct, confounded 

 with the margins, usually inflated at the median portion and at the apices, 

 showing at the apices a very distinct crown of radiant delicate striae; pseudo_ 

 raphe narrow; striae delicate, 13 or 14 in 1 c.d.m., delicately punctate. 

 Length, 17 to 42 c.d.m. 



Marine. Ostend : Oyster beds, very rare. England (Stolt, Norman), Scotland (Kitton in 

 Baxter Coll., No. 4292), Ireland (O'Meara), France. 



S. superba Kutz. (Baa, p. 69, pi. 15, f. 13; w. Sm., s.B.D., i., p. 

 74, pi. 12, f. 102*), plate 30, fig. 834. 



Valve robust, linear, infinitesimally attenuate from the median portion to 

 the apices, which are rounded sub-truncate. Two sulci, extending the length 

 of the valve, distant from the margins, dividing into two parts the portion of 

 the valve situated between the margin and the pseudo-raphe. Striae very robust* 

 punctate, about 10 in i c.d.m. Length, 25 to 50 c.d.m. 



Marine England (Norman, W. Sm.), Ireland (O'Meara). 



S. baculus Greg. (T.M.s., 1857, v., p. 83, pi. 1, f. 54; h.v.h. 



Atl., pi. 42, f. 9*), plate 30, fig. 835. 



Valve very broadly linear, with apices rounded. Sulci confounded with 

 the margins of the valve. Striae delicate, 9 or 10 in 1 c.d.m., undulated, finely 

 divided transversely, in such a manner as to form very approximate 

 longitudinal striae. Length of valve, 40 to 60 c.d.m. Breadth, 1*5 to 3 c.d.m. 



Marine. Coasts of Scotland and Ireland. 



S. robusta Ralfs. (in Pritch. Inf., p. 789, pi. 8, f. 3; H.V.H. Atl., 

 pi. 42, f. 6 and 7* ; Type No. 304), plate 30, figs. 836. 837. 



Valve very broadly linear, with apices somewhat produced, rounded, obtuse. 

 Pseudo-raphe very robust and simulating a sulcus ; two sulci marginal and two 

 others intermediate ; transverse striae robust, about 5 in 1 c.d.m., showing in 

 their intervals fine longitudinal lines, and sometimes an appearance of rows of 

 beads in the middle of each compartment. Length, 50 to 80 c.d.m. Breadth 

 3*25 to 4 c.d.m. 



Marine. This magnificent species, the most beautiful of the Synedra, has hitherto been only 

 found in the Mediterranean and Adriatic. We mention it on account of its singular beauty, its 

 remarkable size, and its very peculiar structure. 



