144. MAZATLAN BIVALVES 



Genus PECTUNCULUS, Lam* 

 196. PECTUxcuLrs in^qtjalis, Soio. 



Proc. Zool. Soc. 1832, pt. ii. p. 196 : [non G-ra?/ in Beech. Voy. 



p. 152, pi. 42, f. 3 : (v. Itve. in P. Z. S. 1843, p. 79 ;) nee 



Krauss, Siulafr. Moll. p. lS.'\—m(nl. Bescr. Cat. p. 166.— 



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

 = P. Pectinifoi-mis, Wood Suppl. pi. 2, f. 11, non ia«i. (teste 



Haul.) 

 ? = P. assimilis, Sow. Proc. Zool. Soc. 1832, pt. ii. p. 196.— Mull. 



St/n. Test. Viv. p. \S<d.—Rve. Conch. Ic. pi. 4, f. 15 .— J5. M. 



Cat. B'Orb. Moll. p. 80. no.712.—C. B. Ad. Pan. Shells, 



p. 256, no. 411. — Sanl. Descr. Cat. p. 167, note. 



Only two specimens haviug been found adult of tkis ex- 

 tremely beautiful shell, no opportunity 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. 

 iuEequalis : 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 iu the "strung fig" pattern. Margin most beautifully 

 crenated hj each ; interior surface covered with fine lines ; 

 anterior part short, ligament subtnmcated. A very young 

 valve, '04 aci'oss, 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. 



Hah. — Bay of Panama and Heal Llejos ; in sandy mud, \0 fm. ; 

 Cuminy. — Mazatlan ; extremely rare ; Lpool Col, — (P. as- 

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

 and gravel 8-12 fm. ; Cuming. — Ecuador, Guayaquil, D'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. — G65, the finest 

 specimen. 



197. Pectukculus P multicostatus, Soic. 



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. 

 I)'Orb.3Ioll. p. SO, no. 711. 



• "The first name for these shells is Aiinaea, PoH. If Pectnnculus, Lam. (oot 

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



