ROCELLARIA. 335 



Tube testaceous, straight, transversely striated, thickened 

 and closed at the fore part, tapering and open anteriorly, the 

 hinder or lower end, when complete, furnished with a per- 

 forated septum behind the valves. 



Syn. Chsena, Eetzius. Fistulana, Lamarck. 



Ex. G. mumia, Spengler, pi. 91, fig. 1. Tube, Gr. 

 mumia, fig. 1, a. 



The curious shell on which Spengler founded this genus 

 is generally known under the name of Fistulana clava, 

 Lamarck ; it is also the type of the Chcena of Eetzius. 

 They are found, at low- water line, in Singapore, the Phi- 

 lippines, and other islands in the Eastern seas, living gregari- 

 ously in the mud and sand in large numbers, the tips only 

 of the tubes being visible above the surface, and the closed 

 ends firmly embedded in the soil. Fossil examples have 

 been detected in the inferior Oolite of the United States, 

 Europe, and Southern India. 



Species of Gastrochccna. 



agglutinans, Desk. mumia, Spengl. 



graudis, Desk. 



Genus ROCELLARIA, Eleuriau de Bellevue. 



Shell with both valves free, cuneiform, equivalve, widely 

 gaping in front, closed behind; valves very inequilateral; 

 beaks anterior. Hinge simple, linear, toothless, but furnished 

 with a small spatulate lamina; ligament external, long. 

 Muscular impressions small, wide apart, united by a slightly- 

 marked, sinuated pallial impression. 



