17 















54 Arca Solida p. 155 9 Formosa p. 160 
55 Auriculata? ge 10 —— Grandis p. 160 
56 Trapezina p. 153 11 Cardiiformis p. 161 
57 Transversa p. 161 12 —— Multicostata p. 161 
58 —— Divaricata p. 155 13 Tetragona p. 152 
59 Pacifica p. 155 14 Truncata p. 156 
60 —— Emarginata(very old) 15 —— Chalcanthum app. 
p. 161 16 Decussata app. (Sul- 
cata? p. 153) 
i, Velata p. 156 
PLATE XIX. 18 Pectunculus Spadiceus arp. 
19 ———— Siculus p. 162 
1 Arca Alternata p. 156 20 ————— Violascens p. 163 
2 Lithodomus p. 156 21 ————— Intermedius p. 
3 Labiosa p. 159 164 
‘4 Concinna p. 160 22 ——__— Ovatus p. 164 
5 —— Obesa p. 160 . 23 ————— Tessellatus pp. 
ne Nux p. 160 166 
7 — Labiata p. 160 24 ——__—_—- Tenuicostatus 
§ —— Glacialis p. 156. APP. 
* This figure is copied from that given in Delessert’s delinea- 
tions of the unfigured specimens described by Lamarck. The ori- 
ginal diagnosis is as follows :— 
‘‘ Cordate, ventricose, with many crenulated ribs; umbones 
oblique; emarginated anteriorly. 14. Indian Ocean. Allied to 
Rhombea, but smaller, mith the beaks more approximated.” The 
figure in Delessert’s magnificent folio, exhibits about thirty very 
closely arranged ribs, and the posterior end of the ligamental area 
destitute of any ligament. I have never met with any specimen 
which I could satisfactorily identify with this engraving; the shell 
which I have described at page 157, (which is a variety of my A 
Deshayesii, the Antiquata of Lamarck’s description, but not that 
of Linnzus,) although sufficiently in accordance with the too brief 
characters, evidently not being identical with the delineated spe- 
cimen. 
