A FOSSIL MARINE DIATOMACEOUS DEPOSIT. 71 



curved outwards ; the other less convex, with a circle of more 

 numerous, straight, slightly T-headed spines. 



(Note. — The above list by no means exhausts the numerous 

 forms belonging to Stephanopyxis in this deposit.) 



Discs similar to that figured by Dr. O.N.Witt (" Simb. Diat.," 

 PI. 11, Fig. 13) as the secondary valve of St. ferox are ex- 

 tremely common here. 



Pyxidicula cruciata, Ehr. (" Prit.," p. 825).— Valve usually 

 oval. Frequent. 



Pyxilla Johnsoniana, Grev. (" T. M. S.," Vol. xiii, p. 3, PL 1, 

 Fig. 6). — This diatom is described by Greville as having free 

 frustules, but the fact of our having observed two valves con- 

 nected by the apiculi, induces us to think that it may be a fila- 

 mentous form. The apiculi are reduced in thickness for some 

 distance from the end, at which place they are connected, looking 

 as if they were spliced together. Frequent. (PI. V., Fig. 10.) 



P. dubia, Gran. ("Van Heurck Syn.," PI. 83, Bis, Fig. 12). 

 — Not infrequent. 



P.?? (Pterotheca, Kitt.), aculeifera, Grun. ("Van. Heurck 

 Syn.," I.e., Fig. 5; also Kitt. in "J. Q. M. C," 1871).— A 

 variety of this is frequent. 



Stejohanogonia danica (Kitt.), Grun. var. (I.e., Figs. 7 and 8). 

 — This form differs from that figured in "Van Heurck Syn.," 

 from the Jutland deposits. The apiculus is more gradually 

 contracted, the angular costce are more strongly developed, 

 and very conspicuous in the valvular view. The valve is oval 

 and hyaline. Frequent. 



Xanthiopyxis oblonga, Ehr. ("Prit.," p. 827, PI. 5, Fig. 76). 

 — Frequent. 



X. constricta, Ehr. ("Prit.," Z.c.).— Frequent up to -0025" in 

 length. 



Liradiscus ovalis, Grev. (" T. M. S.," Vol. xiii, p. 5, PI. 1, Figs. 

 15, 16). — Not frequent. 



Goniothecium odontella, Ehr. (" Prit.," p. 864, PI. 6, Fig. 29 ; 

 also Brightw. in " Q. J. M. S.," Vol. iv, p. 106, PI. 7, Figs. 47, 48). 

 — A variety of this is very common. 



ChcBtoceras gastridium (Ehr.), Grun. var. ("Van Heurck 

 Syn.," PI, 82, Bis, Figs. 1 and 2). — We have observed several 

 specimens of a form closely resembling this, but with incurved 

 awns. 



