SOME NEW AM) RARE DIATOMS 



Trie. ( mtylutn) Ehrenhergii . (E.) Grun., Van H. Syn. 115 f. 7. 8. Valve 

 small, suborbicular; sides convex, undulate: angles acute; margins marked by a row of 

 large cellules: surface covered with radiant rows of faint, minute puncta, diminishing in 

 size toward the centre; a straight, strong spine projecting from the centre. Distance 

 between the angles, .0023 inch. Springfield Estate, Barbadoes. Plate IV, Fig. 12. 



Trie. Hfirrisoniiuiitm. Norm-, and Oreo., Trans. V r . S. 1861 p. 76 pi. f. ?: 



Sch At. 75 f. 14-10: 81 f. 17; forma minnta, 81 1 8, 9. Large; '• Valve with convex 

 sides and slightly pioduced, rounded angles ; pearly granules forming a marginal band 

 of radiating rows and scattered thinly over the ample central space, in which is a con- 

 spicuous network of large, elongated radiating cellules, each cellule containing a blight 

 granule, and sending down lines between the rows to the margin : rows 4 to 6 in .001 

 inch. Variable in size, distance between angles from .004 to .008 inch. Springfield Es- 

 tate, Barbadoes. Plate IV, Figs. 4. 5. 



Var. Solida. W. and C. Valve much smaller, sides straight : angles rounded ; 

 central area faintly reticulate, irregularly cellulate ; the cellulation more dense than in 

 the genuine : border cellulation same as in the large form ; rows of cellules 8 in .001 

 inch ; distance between anghs, .0021 inch. Springfield Estate, Barbadoes, Plate III, 

 Fig. 12. 



B 



Isthmia minima. Bailey and Harvey, Wilkes' Exped., Vol. XVII, p. 176 

 pi. 9 f. 11 : Prit. Inf. p. 851 : H. L. S. Spec. Typ. No. 205. Small, .006 in. loug by 

 .002 in. wide. Cellulation arranged regularly diagonally, similar to that of /. nervosa; 

 much coarser on the end-pieces than on the central band : frustules trapezoidal, one end 

 rounded, the other considerably produced, the process constricted and finely granulate. 

 Springfield Est., Barbadoes. Plate V. Fig. 9. 



Triceratium venosum, BrigldiciU, M. J. 1856 p. 274 pi. 17 f. 5 : Trans. M. 

 S. 1860 p. 147 pi. 7 f. 2 : Prit. Inf. p. 854; Schm. At. 88 f. 11. 12: Journal N. Y. M. 

 S 1886 p. 110 pi. 5 f. 4 Large ; angles slightly elevated above general surface, truncate, 

 not produced, but rounded ; sides concave : surface with three radiant canaliculi ex- 

 tending from the centre two thirds the distance to the apices : shorter parallel canaliculi 

 extending from these to margin of valve ; between each pair are two rows of quite large 

 cellular openings, which are also continued transversely on angles of valve nearly to 

 tbeir full extent. Nodular surface on angles very finely granulated. Distance between 

 angles, .0052 inch. Cambridge Estate, Barbadoes. Plate IV, Fig. 11. 



Forma parva, Weiss/log. Schm. At. 94 f. 12. Characteristics much the same 



