52 



28. haliotidea, Lam. 



29. hippopus, id. 



30. hyotis, C/iemn. 



31. imbricata, Lam. 



32. iridescens, Gray. 



33. labrella, Z«»i. 



34. lacerata, Hartley. 



35. margaritacea, Zff>». 



36. megadou, Hartley. 



37. Mytiloides, Law. 



38. mordax, Gould. 



39. multistriata, Hartley. 



40. numisma, Z«»». 



41. pes-tigris, Hartley. 



42. plicata, Chemn. 



43. pyxidata, ^rf. $• i£. 



44. rosacea, ZtesA. 



45. rostralis, Lam. 



46. ruscuriana, «<5?. 



47. sea bra, w£. 



48. Senegalensis, Gmel. 



49. Sinensis, GWZ. 



50. siimata, Lam. 



51. spathulata, zV?. 



52. spinosa, Quoy. 



53. stentina, Payr. 



54. trapezina, Zam. 



55. tuberculata, id. 



56. turbinata, ic?. 



57. Virginica, Gmel. 



58. Webbii, Recluz. 



Figure. 



Ostrea bicolor. PI. 26. Tig. 159. Shell, with the upper valve lifted 

 on one side to show the hinge. 



Family 2. PECTINACEA. 



Shell ; either free or affixed, mostly inequivalve, generally auricu- 

 lated on either side of the umbo; ligament internal or semi- 

 internal, within a central triangular pit. 



The Pectinacea are numerous in species, and have shells remarkable for 

 their elaborate sculpture and brilliant varieties of painting. The Sportdt/U, 

 in which the umbonal area noticed in Ostrea has its maximum deve- 

 lopment, throws out spines and fronds more profuse and sharply attenu- 

 ated than in any other genus of lamellibranchiates ; and the Pectens, dis- 

 tinguished by a beautiful regularity of growth and vivid colouring, present 

 the first indication of the byssus which is so conspicuous a characteristic 

 in the two succeeding families Aviculacea and Mytilacea. Linked with 

 these are two or three rather abnormal though intermediate forms of striking 

 interest. The sen era are — 



Spondylus. 

 Plicatula. 



HlNNITES. 



Pecten. 



Hemipecten. 

 Lima. 



Pedum. 



Genus 1. SPONDYLUS, Linnaus. 



Animal ; oval or oblong ; edges of the mantle disunited, thick, 

 furnished with numerous rows of tentacular cirrhi, of which 



