PANAMIC-PACIFIC PELECYPODA 441 



Gastrochaena (Kocellaria) orata Sowerby Plate 80, figures 7, 7a, 7b 



Gastrochaena ovata Sowerby, 1834, Proc. Zool. Soc. London, p. 21. Found in Spondyli 

 at the Isle of Perico (Panama), and in coral rock at a depth of 17 fathoms 

 at the island of Plata. — Sowerby, 1878, Conch. Icon., vol. 20, Gastrochaena, pi. 

 3, fig. 18 (not 16).— Sowerby, 188+, Thes. Conch., vol. 5, p. 128, No. 12, pi. 470, 

 fig. 9.— Lamy, 1925, Jour, de Conchyl., vol. 68, No. 4, pp. 304, 305. 



Rocellaria ovata (Sowerby), Hertlein and Strong, 1950, Zoologica, vol. 35, pt. 4, No. 

 19, pp. 246, 247, pi. 2, fig. 2. 



Shell relatively short and high, the length usually between 20 and 30 

 mm. Highest and widest about the middle, the posterior end long and nar- 

 rowly rounded at the end, the anterior side in front of the beaks much con- 

 stricted and somewhat produced. The ventral gap is large and broadly 

 elliptical. Surface sculptured with rather coarse to fine raised concentrics, 

 spaced evenly and widely over the posterior surface, much crowded on the 

 posterior-ventral and anterior side where the lamellae are also obscurely 

 denticulated. Interior of the shell shows vascular markings over much of 

 its surface, the posterior adductor scar large and distinct, weakly joined 

 above with that of the retractor; the anterior adductor scar is also well 

 marked and lies largely in the attenuated portion; the pallial line connecting 

 the adductors is wide, pustulated, or veined, the pallial sinus is deep, reach- 

 ing into the middle of the shell cavity. Hinge line plain, the ligament 

 external. 



A specimen from Manta measures: length 19.2 mm., height 10.6 mm., 

 diameter 9.7 mm. ANSP. 



Range — Lower California south to Ecuador. Also in the Atlantic and 

 West Indies. Mexico: at various localities in the Gulf of California; Mazat- 

 lan (Carpenter). Costa Rica: Uvita Bay (Hertlein and Strong). Panama: 

 Pearl Islands (Cuming). Ecuador: Isla la Plata (Cuming); Manta. 



Gastrochaena denticnlata Deshayes 



Gastrochaena denticulata Deshayes, 1857, Proc. Zool. Soc. London, p. West Colombia. 

 Sowerby, 1878, Conch. Icon., vol. 20, Gastrochaena, pi. II, fig. 8. — Sowerby, 

 1884, Thes. Conch., vol. 5, Gastrochaena, p. 129, pi. 470, fig. 7. 



This species is known only by its figure which shows a shell with a short 

 hinge margin, with an 120 degree angle at the end and strong, denticulated 

 concentric lamellae on the anterior-ventral surface setoff from the posterior 

 surface by a sharp, middle line; this figure is strongly suggestive of a young 

 pholad with a large pedal gap. 



Range — West Colombia (Ecuador). 



Supsrfamily PHOLADACEA 

 Family PHOLADIDAE 



Complex and highly specialized Pelecypoda adapted for boring or bur- 

 rowing in sand, clay, rock or wood, sometimes in coral and the walls of 

 thick-shelled mollusks, the valves usually thin, fragile, and white. In addi- 

 tion to the paired valves on the sides of the animal, smaller accessory plates 

 to the number of four or less may be present in some species, while they 

 are partly or wholly lacking in others; these accessory plates may be paired 



