16 CO^CB-YLIA—DITHYRA. 2. 



dorsalis. Teb.'EDO valvis postice rotundatis inauriculatis clausis, costd longitudi- 

 nali interna. 

 Shell with the valves rounded without auricles and closed behind, 

 furnished with a longitudinal rib on the inside. 

 Tab. nost. 2, fig. 4 and 5. 

 Teredo dorsalis. Turton, Conch. Diet. p. 185. 

 Mus. nost. From a piece of wood in Torbay. 



Shell less than the T. navalis, and is distinguishsd by the want of 

 the reflected ear-shaped processes on the hinder side, where the 

 end is plain and rounded ; by the valves closing together at that 

 part ,• and by the longitudinal jointed rib on the inside of the valves, 

 with a corresponding groove on the outside. On the margin is a 

 raised curved process in one valve and a small slightly cloven one 

 in the other. 



From the circumstance of the valves being enabled to close 

 together at the hinder end, we doubt if it can be furnished with a 

 tube. It merits a better investigation than the few specimens we 

 possess can give it. 



nana. Teeedo valvis postici rotundatis inauriculatis, margine cardinali dente 



conico valido. 

 Shell with the valves rounded and without auricles behind, a strong 

 conic tooth on the margin above the teeth. 

 Tab. nost. 2, fig. 6 and 7. 

 Mus. nost. From a piece of wood in Torbay. 



Shell hardly the eighth of an inch in diameter; something 

 resembling the young of Teredo dorsalis ; but the valves are des- 

 titute of the jointed internal longitudinal rib. The specimens we 



