BY G, I. PLAYFAIR. 121 



NiTZSCHiA vERMicuLARis var. siALis, n.var. (PL v., f.6). 

 Forma a latere cingulato visa, apicibus attenuatis. Puncta 

 carinse 5 in 10 /x. 



Long. 180-186; lat. valv. 8, ap. 3; lat. frust. 14, ap. 8-10 jut 

 Lismore(3, 12); in Lynghya stratum (26). 



Var. MiNUTA, n.var. (PI. v., f.7). 



Forma minima, latere cingulato apicibus attenuatis, punctis 

 carinas saepissime carentibus. 



Long. 44-48; lat. valv. 4, ap. 2^ /x. 



Lismore, in Lynghya stratum (26) cum priori. 



The carinal dots in these forms increase gradually in number. 

 They first elongate longitudinally and then divide into two 

 granules. Granular and elongated puncta were noted inter- 

 mingled in the same specimen, and with them also were some 

 which were quite evidently half divided. It is one indication of 

 a very slow process of growth and development which is taking 

 place in the frustule. 



Genus Tryblionella W. Smith. 

 Tryblionella Hantzschiana var. minor, n.var. (PI. v., f.8). 

 Formae typicse (fig. a in Grun., Oesterr. Diat., T. xii) consimilis 

 sed minor. 



Long. 40; lat. valv. 14 /x. 



Var. YiCTORiiE (Grun.) mihi. (PI. v., f.9-1 1). 

 Long. 30-60; lat. valv. 15-22 ; lat. frust. 13-20, cingul. 5-8 /x. 

 Striae 24-36, 5-6 in 10 /x, equal in number to the marginal dots 

 when present. Syn. Tryhl. Victo7'ice Grun., Oesterr. Diat., p. 553 

 T.12, f.34. Both figures are tilted sideways, 346 very much so. 



Var. calida (Grun.) V. Heurck. (PI. v., f.l2). 

 Long. 70-72; lat. valv. 10-12, ap. 2-3; lat. frust. 11, cingul. 3-4 /u. 



Var. OVATA (Lagerstedt) mihi. (PI. v., f . 1 3). 

 Long. 26-36; lat. valv. 14-18. Strise circ. 20, 6 in 10 /x. Syn. 

 T. ovata Lagerst., Spetzbergens, p. 48, T.2, f.23. Lagerstedt's 

 figure also is tilted sideways. 



