NUCULIOE. 139 



teriorly. Hinder dorsal area large, smooth, lanceolate, much 

 pouting, although so abruptly impressed at its circumference that 

 it seems angularly defined by the higher level of the general sur- 

 face. No lunule. Cartilage-pit very large, broad, eochleariform. 

 Front teeth much the more numerous. — The 'Mineral Conchology' 

 was published before the 'Animaux s. Vertebres/ and long before 

 the ' Zoological Journal.' 



58. L. amygdalea, Valenciennes, f. 8, 10, 11. — T. suba>qui- 

 lateralis, elongato-oblonga, antice auguste rotundata, postice vix 

 brevior et subtruncato-rostrata, sublaevigata, cute nitidissima in- 

 duta, radio utrinque impressa. Margo dorsalis posticus leviter 

 declivis, vix subretusus ; ventralis antice arcuatus, in medio sub- 

 rectiusculus, postice conspicue acclivis. Area baud impressa, vix 

 definita. — Elongated-oblong, fragile, merely convex, subequilateral, 

 yet longer in front, gaping at both extremities, with a shallow in- 

 dentation radiating from the acute beaks (which are reflected and 

 by no means prominent) to both ends of the ventral margin, and 

 obsoletely sinuating them, narrowly rounded in front, subtruncately 

 beaked behind (posterior lip convex), covered with a polished 

 cuticle which is brownish-olive, greenish-olive, or pure olive, in 

 rather broad lighter and darker zones, smooth, except ventrally, 

 where the surface is coarsely and remotely wrinkled concentrically. 

 Dorsal edges little sloping ; the front one convex, the hinder one 

 barely retuse. Ventral edge retusely straightened in the middle, 

 much arcuated in front, convexly rising behind. Escutcheon 

 lanceolate, not sunken, nor sharply defined, merely indicated by 

 a cessation of the convexity, its edges pouting : lunule wholly 

 obsolete. Interior bluish-white : teeth very numerous. 



59. L. limatula, Say, f. 9. — T. amygdalea assimilis, cute 

 autem viridi, lateribus sequis, extremitate rostri cuneiformis an- 

 gusta, et area acute definita. — Allied to amygdalea, but more 

 equilateral, with the posterior indentation inconspicuous, the cu- 

 ticle light green (with an occasional linear darker zone of growth), 

 the beak more decided and cuneiform, with its tip narrower, 

 upturned, and not at all truncated, the anterior extremity more 

 broadly rounded, the ventral margin more rising posteriorly. 

 Escutcheon sharply defined by the very abrupt cessation of the 

 general convexity. Lunule linear, perceptible. Teeth numerous 

 on both sides (often 28-20). 



60. L. arctica, Gray, f. 5. — T. ovalis, convexa, l&'vis, sub- 

 aequilaterahs, cute nitida olivacea zonisque saturatioribus ornata. 

 Extreuiitas lateris postici brevioris et obtuse aeuininati rotun- 



