139 



34. obliqua, Wood. 



35. orbiculata, Say. 



36. pallida, Sow. 



37. proxima, C. B. Ad. 



38. pulchella, Adams. 



39. pulchra, Sow. 



40. punctata,, id. 



41. purpurascens, Soto. 



42. radiata, Riipjp. 



43. reticulata, Sow. 52. 



44. rosea, id. 53. 



45. rubro-lineata, Conr. 54. 



46. rupium, tfow. 55. 



47. scabra, i/«M?. 56. 

 4 8 . simplex, Ad. 8f Reeve. 5 7 . 



49. Sinensis, Adams. 58. 



50. solida, Gray. 59. 



51. sponsa, Adams. 



striata, Riipp. 

 subtrancata, Sow. 

 tortuosa, C. B. Adams. 

 ventricosa, id. 

 venusta, Adams. 

 vestal is, id. 

 virgin ea, id. 

 Zebuensis, Hani. 



Figure. 



Amphidesma obliqua. PI. 39. Fig. 216. Shell with one valve dropped 

 to show the oblique posterior pit containing the ligament. 



Genus 3. UNGULINA, Baudin. 



Animal ; with the mantle open beloio, fringed ; siphoned orifice 

 single ; foot vermiform, thickened at the end and perforated, 

 projecting from the base of the shell, or folded up between the 

 gills. (Woodward.J 



Shell ; suborbicular, equivalve, nearly equilateral, covered with 

 a thick brown epidermis ; hinge composed of a short central 

 bifid tooth in each valve, ivilh an additional small one in one 

 valve only ; no lateral teeth ; ligament in a narrow oblique 

 marginal pit. 



Ungulina is a mollusc of very peculiar habits, producing a very peculiar 

 shell. Three species only are known, and they are found on the shores of 

 the Mediterranean and Red Seas, either buried in sand or mud, or excava- 

 ting winding galleries in coral. The shell is covered externally by a dark 

 chestnut-brown horny epidermis; internally it is sometimes tiuged with 

 patches of blood-red. The hinge so far resembles the hinge of Amphi- 

 desma, that it has an oblique narrow pit containing the ligament, and it 

 has the central bifid tooth in an obtuse .somewhat undefined form. The 

 general outline of the shell varies in being oblong or transverse according 

 to the nature of its place of habitation. 



