538 PROFESSOR GREGORY ON 
lata (Ehrenb., l. c., tab. xix., fig. 13) which is represented with three terminal 
teeth ; but these teeth can scarcely be the remains of a corona, as Krzine, in de- 
fining the frustule, says, “utroque fine medio apiculis elongatis hispido.” Upon 
the whole, the safe course seems to be to regard the subject of this notice as not 
only specifically but generally new; and I gladly adopt the suggestion of Pro- 
fessor WALKER-ARNOTT, that it receive the name of Cresellia in honour of its dis- 
coverer, the Rev. R. CrESwELL, a gentleman well known to Algzeologists, and to 
whom Professor Harvey has already dedicated a new British Schizothrise. The 
following character will distinguish it at once from all its allies. 
Creswellia. Frustules cylindrical, two-valved, cohering by short, filiform pro- 
cesses into a continuous filament. Valves cup-like, cellulate, destitute of any si- 
liceous connecting band. PI. XIV., fig. 109. 
This singularly interesting Diatom, which may be called Creswellia Turris, 
has only been found in the locality already mentioned by Mr Creswe tt, and off 
the Island of Cumbre, where it was dredged along with the nests of Lima hians 
by Mr Hennepy, and a single frustule detected by Dr WALKER-ARNOTT. 
The figure represents four frustules, the largest number which has been 
hitherto observed in connection. It will be perceived that in two of the frustules 
one of the valves is dark, and more or less opaque. This appearance we are quite 
unable to account for. It sometimes happens that the whole frustule is dark. 
Generally they are all beautifully clear. The structure is highly cellulate, the cells 
hexagonal. The length of the frustule is about -0028"; the breadth about -0016’. 
EXPLANATION OF PLATE IX. 
Fig. 1. Nayicula minor, n. sp. Fig. 16. Navicula Smithii, var, y, nitescens. 
= 2a Cluthensis, n. sp. =) Ol 76, Dee Smithii, var. 6, suborbicularis. 
— 3. inconspicua, n. sp. — 18&18b, maxima, Greg., 8.V. and F.V. 
— 4 brevis, n. sp. — 19. Pinnularia subtilis, n. sp. 
= ES Clayiculus, n. sp., S.V. x 800.)— 20. ... rostellata, n. sp. 
DOMAO.seLVs x SOOO! Sie; don! == S21 ae: Allmaniana, n. sp. 
S.V. x 400. =) 22. +) one Pandura, Bréb., var. 8. elongata. 
— 6 .. Musca, n. sp. — 23, Cocconeis distans, Greg. 
Teale rectangulata, n. sp. — 24... ornata, n. sp. 
— 8 : nebulosa, n. sp. — 25... dirupta, n. sp. 
——ReOs aiace Barelayana, n. sp. — 2. ... nitida, n. sp. 
—— LO’ YE. spectabilis, n. sp. — 27, ..  pseudomarginata, n. sp. 
La iaicn praetexta, Ehr. at 2G * wave major, n. sp. 
12. Bombus, Ehr, — 29. ... splendida, n. sp. 
— 1388136, Lyra, Ebr. All the above, except figs. 5 and 5 b, are magnified 
— 14&14b, Lyra, var. B. 400 diameters. 
SWS ee Smithii, var. 6, fusca. 
EXPLANATION OF PLATE X. 
Fig. ay Denticula (?) interrupta, n. sp. Fig. 34. Denticula nana, n. sp., F.V. 346; do. S.V. 
— sly tesa (2) capitata, n. sp, — 35,356, & p 7 ‘ 
= 52. nv (?) ornata, n. sp. 35.¢, } minor, n. sp. F.V. 35d; do. S.V. 
— 33,33), & ) (2) levis — 86. ...  distans, n.sp., F.V.366; do. S.V.. 
Gato, yaa 5 — 37&387b,...staurophora, n,sp.,F.V.37¢; do.S.V 
