I. Tabula diagnostica

kkX

. Concha maxima, margine superiore horizoutali, inferiore con- Cavo : (A. CYGNEA).

2. C. magna, marg. super. et infer. subhorizontal, et parallelis : (A. Cellensis).

3. C. intermedia, crassiuseula, marg. super. et infer. fere paral-

lelis : (A. oblonga).

XAX

4. C. mediocris aut minor, subrhombea, compressa, nitida, marg, super. et infer. plerunque subparallelis : (A. cOMPLANATA).

Le oS

Cr

. C. mediocris, breviuscula, marg. super. arcuato, infer. horizontali : (A. ANATINA).

6. C. intermedia, elongato-rostrata, marg. sup. subarcuato, infer. horizontali : (A. Moulinsiana).

7. C. minor, elliptico-lanceolata, margelio cœruleo : (A. Rayii).

8. C. minima, elongata, fragilis, marg. super. arcuato, infer. subhorizontal : (A. parvula).

kXk 9. C. intermedia vel majuseula, crassiuscula, eleganter colorata, marg. super. arcuato, infer. CONCavo : (A. PISCINALIS).

40. C. majuscula, brevis, lruucata, ventricosa, crebrisulcata, marg. super. ct infer. arcuatis: (A. Milletii).