TRIBE NYMPHACEA. 81 



D Btcolor. Lam. 13. — An. D. Bicolor. Gmel.no. lO.'l 

 — Gualt. t. 88./. 5 —List. t. 392. /. 231. Ovate, wedge-shaped, 

 whitish stained with brown, with a few longitudinal striae, decus- 

 sating still fewer transverse ones : anterior end with waved and curled 

 furrows : spotted with violet within. — Mauritius or India. 



D. Vittata. Lam. 14. — Del. t. 6.f. 12.— D. Biradiata and 

 Sexradiata. W. S. Ovate, rather depressed, with transverse 

 groove-like striae ; whitish with a very few rufous rays, which en- 

 large as they approach the margins. — Mediterranean.* 1 



D. Lessoni. Desk. E. 3. p. 99. no. 15. Triangular, smooth, 

 depressed, sub-equilateral, pale fulvous with numerous brown in- 

 terrupted rays, and the apex acute : within brownish white, and the 

 margin quite entire and gaping at one end : one of the lateral teeth 

 very long, the other indistinct. — Chili. — Tolerably large, and the 

 length and breadth nearly equal. 



D. Corbuloides. Desk. E. 3. p. 99. no. 18. Triangular, 

 gibbous, equilateral, polished and heart-shaped : pink with elegant 

 waved or angulated reddish yellow transverse lines ; brownish red 

 within. 



D. Equilatera. Sow. Tank. Cat. — D. Veneroidea. Gray, 

 — Venus Donacina. Ch. f. 1983, 4. Sub-triangular, sub- 

 equilateral, the slopes nearly straight, ventral edge arcuated and 

 ascending towards the anterior and longer extremity ; strong, con- 

 vex, white covered with angular sub-reticulated markings of ochra- 

 ceous brown and obsoletely rayed : disc smooth, sides with distant 

 concentric grooves : anterior slope rounded, towards the beaks 

 edged with radiating sub-granulated striae, elsewhere smooth : inside 

 white, margin entire, three approximate cardinal teeth in one valve, 

 two and a rudimentary in the other ; no lateral. I . . \\. — S. Seas. 



J). Owenii. Gray in B. M. Extremely elongated, 

 smooth, polished ; anterior side obliquely truncated and very 

 short, its slope concentrically striated, and its dorsal edge 

 much sloping ; broad white rays on a drab ground, a short narrow 



pressed and perfectly smooth ; anteriorly very short, very convex, 

 with very fine radiating striae, which are very indistinct, except on 

 the slope ; umbonal ridge angulated near the smooth beaks ; ven- 

 tral edge arcuated : inside stained with purple : receptacle of the 

 lateral tooth very prominent. 1^.-2. 



2 D. Triquetra. Lam,] 5. Triangular, sub-equilateral, glossy, 

 much swollen under the beaks, whitish with fine transverse striae, 

 and a few vestiges of rays : and indistinct violet spot within. J-. — 

 JSfew Holland. ~(A young variety of Cytherea Corbicula. 

 Desk.) 



G 



