NO. 1312. SYNOPSIS OF'THE VENERID.E—DALL. 367 



This is the most compressed and dark-colored of our East Coast 

 species and has liner and closer striation than any of the others. It is 

 the Artemis or Dosinia concentrica of the earlier American writers, 

 but not of Born. The color which resides in the periostracum is fre- 

 quently distributed in darker and lighter zones. 



TRANSENNELLA CUBANIANA Orbigny, 1847. 



Cape Florida to St. Croix, West Indies. 



A small, usually pure white species, living- in 8 to 30 fathoms, and 

 especially abundant in Porto Rico. It was inadvertently and errone- 

 ously referred to Gouldla in the report on the Blake moUusks. 



TRANSENNELLA STIMPSONI Dall, 1902. 



Cape Hatteras, Egmont Key and south to Key West, in 15 to 31 

 fathoms. 



White, with brown lineation or maculation externally, and orange or 

 deep purple internally, in the central part of the valves. By an acci- 

 dent this species was hgured" for the following species, which is a 

 smaller and more rostrate shell. T. stimpsoni is the largest and pret- 

 tiest of the genus so far recognized. 



TRANSENNELLA CONRADINA Dall, 1883. 



St. Andrew Bay, on the north coast of the Gulf of Mexico in west- 

 ern Florida, south to the Florida Keys and north on the east coast of 

 Florida to Palm Beach, near low- water mark. 



This peculiarly cuneate species has much the same range of color as 

 T. diiHj)son!^ but is different in form. 



TRANSENNELLA CULEBRANA Dall and Simpson, 1901. 



Culebra Island, Porto Rico. 



A specially trigonal, short form, white inside, and light yellow brown 

 externally. 



TIVELA ABACONIS Dall, 1902. 



Abaco, Bahamas, and Vera Cruz, Mexico. 



Shell small, subtranslucent, of a warm rose color, passing into white 

 distally. It is notable for having only three cardinals in each valve. 



TIVELA MACTROIDES Born, 1778. 



Bahama Islands and through the West Indies and adjacent continen- 

 tal shores and south to Santa Caterina, Brazil. 



This species may be white, or chestnut ))ro\vn, or with l)ro\VM rays 

 on a lighter ground. The form is almost as variable as the coloration. 

 The adults appear to have more tumid umbones and a longer and more 



«Proc. U. S. Nat. Mus., XXIV, pi. xxxi, figs. 5 and 7. 



