nuculidje. 155 



tant, the hinder ones close. Ventral margin crenated within, 

 much arcuated, rising behind. Anterior extremity well rounded, 

 front dorsal slope convex. Posterior side very short, not at all 

 projecting below, yet obsoletely subangulated. Neither beaks 

 nor lunular region prominent. 



18. N. castrensis, Hinds, f. 148. — T. elliptica, antice (i.e. 

 postice) rotundata, epidermide olivacea induta; lineis divaricatis; 

 marginibus ventralibus crenulatis ; cardiue antice dentibus 5, 

 postice 11. 



19. N. mirabilis, Ad. and Reeve, f. 114. — T. ovali-truncata, 

 subventricosa, cute lutea baud nitida induta, undique divaricatim 

 arcuate costellata ; costellae antics? cum costellis posticis angulos 

 acutos in medio testae formantes. Extremitas postica interne 

 oblique rectangularis. Margo ventralis utrinque acclivis, antice 

 arcuatus, postice subsinuatus. Area baud circumscripta. Lunula 

 magna, profunda, costellis parvis densisque transversim ornata, 

 angulo circumscripta : angulus divaricatim sculptus. — Truncated- 

 oval, subventricose, with a dull dirty-yellow epidermis, everywhere 

 finely and somewhat arcuatedly ribbed : the front and hinder ribs, 

 which are rounded and narrower than their intervals, diverging 

 from each other at acute angles just behind the middle of the 

 shell ; a similar double divergence along the angular circumference 

 of the large and strongly impressed lunule, which latter is barred 

 across by much denser and smaller ribs. Anterior side produced, 

 somewhat tapering, and well rounded at its extremity ; its dorsal 

 slope rather slight, convex. Posterior side short, obliquely rec- 

 tangular below (in the adult). Ventral margin much arched in 

 its anterior ascent, more or less retuse (with age) just before the 

 end of its posterior ascent. No defined front dorsal area, but the 

 ribs are there denser and more numerous. Umboes rather pro- 

 minent ; beaks obliquely coiled, recurved. 



20. N. divaricata, Hinds, f. 151. — "T. elliptica, antice (i.e. 

 postice) excavata, subacuminata, postice (i.e. antice) rotundata; 

 lineis divaricatis striata ; marginibus ventralibus crenulatis ; 

 cardine antice (i.e. postice) dentibus 7, postice (i.e. antice) 22- 

 24." — Were it not that the described number of the teeth is much 

 greater in the smaller shell, I should have believed this to be an 

 immature mirabilis. 



21. N. Malabarica, Rank//, f. 152. — T. minuta, trigona, baud 

 elongata, satis obliqua, tantum ad umbones angustos et elevatos 

 ventricosa, superne rectangulata, nitida, undique concentrice cos- 

 tellata : sulci interstitiales liris radiantibus exilibus ornati. Latus 



