A FOSSIL MARINE DIATOMACEODS DEPOSIT. 75 



stalked processes, terminating abruptly in nodular, discoid, or 

 cup-shaped expansions, cellulose, but not furnished with claws 

 or hooks, as in Hemiaulus. Other characteristics, those of 

 Biddulphia as defined by Van Heurck (" Syn. Texte," p. 203). 

 Kittonia elaborata, Gr. and St. (Biddulphia elahorata, " J. Q. 

 M.C.," Vol. ii., Ser. n., p. 325, PI. 18, Fig. 9).— This diatom 

 occurs frequently in all the samples of this deposit we have 

 hitherto examined. Specimens vary in size from '007" to '01" 

 in length, and -004" to -0067" in breadth. 



[We take this opportunity of correcting an error in the scale 

 of measurement attached to PI. 18, Fig. 9, which should be 400, 

 not 500 diameters.] 



K. virgata, Gr. and St. (Biddulphia virgata, I.e., p. 325. 

 PI. 18, Fig. 11). — Since the above-mentioned figure was en- 

 graved we have met with a more perfect specimen, of which 

 we now give a figure (PI. VI., Fig. 23.) 



Note. — Having, through the kindness of W. Carruthers, 

 Esq., F.R.S., of the Nat. Hist. Mus., been enabled to examine 

 Dr. Greville's authentic specimens of his Biddulphia gigantea 

 (" T. M. S.," Vol. xii., p. 13, PI. 2, Fig. 9), we find that the 

 hyaline stalked processes terminate in nodular cellulose expan- 

 sions larger than the small capitate ends shown in his figure. 

 We venture to remove the form to this genus under the name 

 of Kittonia grevilliana. 



Cerataulus polymorphus (Kiitz. ), forma minor, ("Van Heurck 

 Syn.," PI. 105, Figs. 3 and 4). — A small form occurs very 

 rarely, which we place here. It differs only in the presence of 

 a small central group of spines, in place of the two shown in 

 the Fig. referred to. 



Triceratium rugosum, n. sp., Gr. and St. — Very similar in 

 general appearance to Trinacria heibergii, Kitt. (" J. Q. M. C.," 

 1871, p. 169, PI. 13, Fig. 6), but differing essentially in the form 

 of the processes, which are large, club-shaped, and studded with 

 short spines. Margin convex, extending beyond the edge of the 

 valve. Surface covered with scattered papillae, presenting a 

 rugose appearance. Length of side about '005". Rare. (PI. 

 V., Fig. 4.) 



T. coscinoides, Gr. and St. ("J. Q. M. C," Vol. n., Ser. n., 

 p. 327, PI. 19, Fig. 13), var. quadrata. — Since describing this 

 species we have met with a four-angled form of the same. 



