144 MAZATLAN BIVALTES 



GENUS PECTUNCULUS, Lam* 

 196. PECTUNCULUS INJEQUALIS, Sow. 



Proc. Zool. Soc*1832, pt. ii. p. 196 : [non Gray in Beech. Voy. 



p. 152, pi. 42, f. 3 : V. Rve. in P. Z. S. 1843, p. 79 ;) nee 



Krauss, Sudafr. Moll. p. 18.] Hani. Descr. Cat. p. 166. 



Eve. Conch. Ic. pi. 4, f. 16. 



= P. Pectiniformis, Wood Suppl. pi. 2, f. 11, non Lam. (teste 



Hani.) 



? = P. assimilis, Sow. Proc. Zool. Soc. 1832, pt. ii. p. l^.Mull. 

 Syn. Test. Viv. p. 189. Eve. Conch. Ic. pi. 4, f. 15. 5. M. 

 Cat. DOrb. Moll. p. 80. no. 712. C. S. Ad. Pan. Shells, 

 p. 256, no. All Hani. Descr. Cat. p. 167, note. 

 Only two specimens having been found adult of this ex- 

 tremely beautiful shell, no opportumiy existed for ascertaining 

 its power of variation; but C. B. Ad. thus remarks of P. 

 assimilis, "In respect of colouring (no two being alike) the 

 species does not appear to be well distinguished from P. 

 insequalis : nor is the distinction in sculpture much more con- 

 stant." Surface of the shell with a variable, small number of 

 ribs, covered, as well as the interstices, with fine ribs decussa- 

 ted in the "strung fig" pattern. Margin most beautifully 

 crenated by each ; interior surface covered with fine lines ; 

 anterior part short, ligament subtruncated. A very young 

 valve, '04 across , displays 3 teeth on each side, with the larger 

 ribs only developed outside and decussated : ligament in a pit 

 as in Limopsis. Long. 1'33, lat. 1*31, alt. '9. 

 Hob. Bay of Panama and Real Llejos ; in sandy mud, 10 fm. ; 

 Cuming. Mazatlan ; extremely rare ; Ifpool Col, (P. as- 

 similis) Puerto Portrero, Bay of Guayaquil ; in sandy mud 

 and gravel 8-12 fm. ; Cuming. Ecuador, Guayaquil, I? Orb- 

 igny. Panama ; under stones, in calcareous gravel, between 

 one-quarter tide and low water mark, rare ; C~B. Adams. 

 Mazatlan, Lieut. Green. 



Tablet 664 contains the smallest valve. 665, the finest 

 specimen. 



197. PECTUNCULUS ? MULTICOSTATUS, Sow. 

 Proc. Zool. Soc. 1832, pt. ii. p. 195. Eve. Conch. Ic. pi. 5, 

 f. 26 Hani. Descr. Cat. p. 165, pi. 19, f. 36. #. M. Cat. 

 DOrb. Moll. p. 80, no. 711. 



* " The first name for these shells is Axinsea, Poll. If Pectnncnlus, Lam. (not 

 Adansori) is to be used, it should be limited to the ribbed species." A. Adams, ms. 



