5IAZATLAN BIVALVES 21 



Smallest siDeeimen, long. '018, lat. '03, alt. '015, 

 Largest „ „ -13, „ -21, „ -12. 



Sah. — Mazatlan ; a small colony were found nestled, and 

 greatly incommoding each otker, in empty Balaui on Miirex 

 princeps : Havre Col. 



Tablet 73 contains 1 specimen in situ, in Balanus ; 3 others 

 of different ages. 



29. RUPELLAEIA , sp. ind. 



Tablet 74 contains a fragment resembling R. foliacea, De.'ili . 

 Mazatlan ; with strong radiating ribs crossed by erect and beau- 

 tifully imdulated laminee. The sculpture smoothes off at the 

 hinge margin. 

 Sab. — Mazatlan ; from the back of a Spondylus Lamarckii ; 



L'pool Col. 



Family COEBULIDyE. 

 Genus COEBULA, Bmy. 



30. CoEBULA BICAEINATA, Sou\ 



Proc. Zool. Soc. 1833, p. m.—Mull. Syn. Test. Jlv. p. 229.— 

 Bve. Conch. Ic. 1844, pi. 3. f 2d.—Sanl. in TFoocr.^ Suppl. 

 Ind. Test. pi. 12, f 31.Sanl. Descr. Cat. p. m.—B. 31. Cat. 



. !>' Orb. IIoll. IX 70, no. 619. 



Shell extremely swollen, the valves nearly equal, sometimes 

 one a little overlapping the other at the posterior ventral margiir. 

 Epidermis thin over the body, thick over the margins of the 

 valves. Irregidarly concentrically striated over the surface, 

 very finely between the i^osterior keels : umbonal portion 

 smooth. Within, ligament affixed to the smaller tooth : pos- 

 terior muscidar scar rounded, on a projecting support : a 

 smaller one behind -. anterior scar oblong. Pallial line simple. 

 In the 3 specimens which alone I have had an opportunity of 

 examining, which are qiute fresh, I cannot detect any pallial 

 sinus. Those who have plenty of Coi'bula; would do well tn 

 examine their interiors, which are not generally noticed in the 

 descrii)tions. They are either very rare at Mazatlan, or have 

 escaped detection, scarcelj'' a dozen sijecimens having been 

 found of aJJ the species. Long. 2' 7, lat. '36, alt. '28. 



Hah. — In sandy nuid, 7 — 17 fm., Panama, Eeal Llejos, Caraecas, 

 St. Elena, Cuming. — West Columbia, Hanley, Jay. — Ecuador, 



