TEBEBRATULA. 13 



specimens off the east coast of Greenland at the several 

 depths of 108 and 228 fathoms. 



According to Mr. Barrett, this is more lively than 

 T. caput-serpentiSj moving often on its pedicle, but it is 

 more easily alarmed. The excellent Montagu must have 

 indulged in an unusual nap when he imagined that the 

 animal protruded its tube through the aperture of the 

 beak, so as to serve the triple purpose of mouth, foot, 

 and sucker, and that it was capable of a certain degree 

 of locomotion ! But his notion that, by means of the 

 hinge, the valves are similarly and as firmly articulated 

 as the claw of a crab, is much more correct, and shows 

 his admirable power of observation. The internal skele- 

 ton is very different from that of T. (Waldheimid] au- 

 stralis. Having carefully cleaned the inside of a speci- 

 men of T. cranium, containing the dried remains of the 

 animal, with a weak solution of potash, and examined 

 several other perfect shells of different ages, I could not 

 perceive the least appearance of a loop, which is so 

 evident in T. australis. The lamellar processes in the 

 lower valve of T. cranium are equal in length, and end 

 in sharp points. They may be compared to the chariot- 

 blades used by the ancient Scythians, and they some- 

 what resemble the falciform apophyses of Teredo and 

 Pholas. In the young of T. cranium these processes are 

 extremely short. Their arrangement and shape are so 

 dissimilar in species closely allied in other respects, that 

 I should be inclined to consider their importance, as 

 characters of generic distinction, somewhat doubtful. 



T. cranium was at first mistaken by Professors Fleming 

 and Sars for T. vitrea, which is a native of the Mediter- 

 ranean, and has a different foramen and skeleton. Dr. 

 Leach gave the present species the name of T. glabra, 

 and its habitat " the coasts of Devon." The young have 



