APPENDIX. 371 



/. 5. Cordate-subtrapeziform, very obliquely transverse, moderately 

 strong, tumid, glossy, yellowish white, stained and spotted with 

 ruddy flesh-colour in front, ridged throughout, except on the concave 

 anterior slope, with numerous rounded lyrae ; ventral edge sub- 

 arcuated, retuse in front; anterior side much produced, its extremity 

 obliquely biangulated, the edge rectilinear ; umbonal ridge pro- 

 jecting, carinated. l...l£. China. The ridges are not so close or 

 numerous as in I. Vulgaris. 



On Arca (p. 151). The description of A. imbricata (p. 152) is 

 from Bruguiere, but unless both Reeve and myself should be mis- 

 taken, the expression " rhomboidal oblong " would be more appro- 

 priate than "ovate." The copied synonymy is not to be trusted to. 

 A. cardissa (p. 153) is only a distorted tetragona, (p. 152); A. Gai- 

 mardi (p. 155) a form of A. lactea (p. 154). Wood's figure of 

 A. Brasiliana (p. 158) does not exhibit the features of that shell. 

 For additional species consult the monograph by Reeve (Conch. Ic.) ; 

 see, likewise, Ann. Nat. 1842, Lesson in the ' Coquille,' J. Philad. 2, 

 Zeit. Mai. 1845, 1847, 1848, 1851, D'Orb. S. Am. and Cuba Shells, 

 Pr. Bost. 2, 3, J. Conch. 2, and Dunker's Guinea Shells. 



Area tetragona, p. 152, t. 19, f. 13 ... A. imbricata, p. 152, t. 18, 

 f. 35 ... A. trapezina, p. 153, t. 18, f. 56 ... A. gradata, p. 155, 

 t. 18, f. 39 ... A. Paciftca, p. 155, t. 18, f. 59 ... A. divaricata, 

 p. 155, t. 18, f. 58 ... A. solida, p. 155, t. 18, f. 54 ... A. truncata, 

 p. 156, t. 19, f. 14 ... A. alternata, p. 156, t. 19, f. 1 ... A. velata, 

 p. 156, t. 19, f. 17 ... A. mutabilis, p. 156, t. 18, f. 52 ... A. litho- 

 domus, p. 156, t. 19, f 2 ... A. glacialis, p. 156, 1. 19, f. 8 ... A. anti- 

 quata, p. 157, t. 18, f. 50 ... A. Deshayesii, p. 157, t. 18, f. 42 ... 

 A. incongrua, p. 159, t. 18, f. 44 ... A. labiosa, p. 159, t. 19, f. 3 ... 

 A. pexata, p. 159, t. 18, f. 43 ... A. concinna, p. 160, t. 19, f. 4 ... 

 A. obesa, p. L60, 1. 19, f. 5 ... A. labiata, p. 160, t. 19, f. 7 ... A. nux, 

 p. 160, t. 19, f. 6 ... A. formosa, p. 160, t. 19, f. 9 ... A. grandis, 

 p. 160, t. 19, f. 10 ... A. emarginata, p. 161, t. 18, f. 60 ... A. tuber- 

 culosa, p. 161, t. 18, f. 53 ... A. Cardiiformis, p. 161, t. 19, f. 11 ... 

 A. multicostata, p. 161, t. 19, f. 12 ... A. transversa, p. 161, t. 18, 

 f. 57 ... A. auriculata, list of plates, p. 17, t. 14, f. 55. 



* (Byssoarcm). Ventral edge hiant, not regularly toothed or 



notched. 



Arca imbricata (t. 18, f. 36), Poli, t. 25,/. 10, 11, teste Phil. 1, 

 p. 58. — A. pulchella, Reeve, I. Arc. f. 122. Small, subrhombic, 

 subventricose, very inequilateral, of an uniform dirty white, densely 

 fimbriated by broad membranaceous lamellae, which are crimped 

 throughout by shallow radiating sulci, that are divergent on the re- 

 tuse umbonal slope : ventral edge incurved in the middle, curving 



