110 



NEW DIATOMS. 



The following New Species of Diatoms are described by Mr. F. 

 Kitton, in the " Monthly Microscopical Journal" for Nov., 

 1873. Chiefly exotic. 



Aulacodiscus superbus. Kitt. —Valve with a large central hep- 

 tagonal depression, processes placed on the margins of the seven 

 cuneate inflations. The heptagonal area marked with large hemi- 

 spherical elevations, less conspicuous on the remainder of the valve, 

 the surface of which (with the exception of a small central smooth 

 space) is covered with distinct radiant moniliform striae ; striae 

 about 18 in '001 in. ; diameter of valve '0050 in. ; length of sides 

 of heptagon, -0033 in. [M. M. J. pi. xxxviii., fig. 1.] 



Clark's Cliff, Barbadoes. 



Stictodiscus Crozierii. Kitt.— Valve with numerous irregularly 

 undulating costse, which become very delicate as they approach the 

 centre, within a short distance of the margin they divide, the spaces 

 between the costae distinctly punctate, central puncta large, scattered, 

 diameter of valve '0064 in. [M. M. J., pi. xxxviii., f. 2.] 



Plentiful in a gathering made by Capt. Crozier, in the Mauritius. 

 Rare in scrapings from a Haliotis shell, West Indies. 



Isthmia? vitrea. Kitt. — Frustules trapezoidal, the opposite cor- 

 ners of the ends more or less produced, hyaline, valves oval or sub- 

 orbicular. [M. M. J., pi. xxxviii., f. 3.] 



Shell scrapings, Sandwich Islands. (R. M. Browne.) 



Nitzschia ventricosa. Palmer. — Frustules linear, lanceolate ; 

 apices obtuse ; valve with ventral margin convex ; dorsum straight 

 or slightly convex ; apices very much produced, awn-like ; keel sub- 

 marginal, punctate, puncta reaching to the extremities of the awn- 

 like ends ; striae faint, distant, about 13 in '001 in. [M. M. J. 

 pi. xxxviii. f. 5.] 



Hong Kong (Palmer). Rio de Janeiro and Bahia (Capt. 

 Perry). 



Nitzschia decora. Kitt. — Valve linear, elliptical, somewhat 

 deeply constricted at the centre ; ends subacute ; keel marginal, 

 punctate ; length -0055 in. ; striae moniliform, distinct, about 36 

 in -001 in. [M. M. J., pi. xxxviii. f. 6.] 



Bahia (Capt. Perry). 



Txyblionella conspicua. Kitt.— Valve elliptical, with central 

 constriction, ends broadly rounded ; one of the margins punctate, 

 puncta conspicuous, about 12 in -001 in. ; centre of valve with a 

 longitudinal elevation gradually sloping towards the margins ; 

 striae obsolete. [M. M. J., pi. xxxviii. f. 7.] 

 Scrapings from Tredacua shells, West Indies. 



