166 DIMYARIA. 



Genus 70 TEREDINA Lamarck. 



Generic Character. — Tube testaceous, tubular, cylindri- 

 cal, closed at the posterior extremity, but exhibiting the 

 two valves of the shell ; anterior extremity open. 



Teredina personata. — The Masked Teredina. Plate 

 XVIII. fig. 22. Shell consisting of a straight tube, with a 

 club-shaped termination, the club consisting of several 

 sinuses and lobes, and resembling a mask. Fossil from 

 Courtagnon. 



Genus 71 — SEPTARIA. —ZawarcA. 



Generic Character. — With a very long testaceous tube, 

 gradually attenuated anteriorly, and appearing as if divided 

 interiorly by vaulted unfinished partitions; anterior end of 

 the tube terminated by two other slender tubes, which are 

 not divided. 



There can be no doubt but that the sheath encloses a bivalve, but 

 as no perfect specimen has hitherto been found, the fact has not been 

 authenticated. 



Septaria arenaria. — The Sand Septaria. Plate XVIII. 

 fig. 23. Tubular, tapering, terminating in a slender undi- 

 vided tube. Found in sand on the shores of the Indian sea. 



Genus 72— FISTULANA — Lamarck. 



Generic Character. — With a tubular testaceous sheath, 

 more tumid and closed behind, and attenuated at the ante- 

 rior end ; open at the summit, and containing an unattached 

 bivalve shell; valves of the shell equal, and gaping when 

 shut ; animal provided with two tubular appendages in 

 front. 



Lamarck ascertained that the testaceous tubes were not the shells 

 themselves, and that the attached bivalve was sueh. 



Flstulana gregata. — The Gregarious Fistulana. Plate 

 XVIII. figs. 24 to 26. Sheaths club-shaped, aggregated; 



