Fam. 33.] NATURAL HISTORY SOCIETY. 113 



the shell from umbo to base ; posterior end widely, the other 

 slightly gaping ; interior rib-like process slender, curved ; one 

 extra valve over the umbones, ovate-triangular, white. L. 20 ; 

 H. 11 ; W. 12 ; U. J. — Connecticut and south. Boring in wood 

 and oyster shells. 



2. Martesia Smithii, Try. Shell short, ovate ; in other points, 

 much like the preceding except that there are two extra valves 

 at the hinge margin, the large one just over the umbones, and the 

 small one in front of it. L. 15; H.IO; W. 12; U. J.— Staten 

 Island. In oyster shells. 



Family 33. TEREDID/E. 



Animal worm-shaped, its two long siphons furnished at their 

 ends with two limy pieces called pallets ; valves gaping, short, 

 with an internal spoon-shaped process extending from the hinge. 

 Animal and valves contained in an irregular limy tube, with 

 which it lines its burrows in timber or clay. 



* Pallets with the blades not feather-like 1. Teredo. 



* Pallets with the Wades composed of joints, making them feather-like 



2. Xylotrya. 



1. Teredo, L. The Ship Worms. 



Shell globular, open widely at both ends, lodged at the inner 

 end of a burrow which is entirely lined with shell ; valves three 

 lobed, the hinge plate reflected over the umbones, and having a 

 long, tooth-like process under each. The extra valves (pallets) are 

 spatulate in form, and are found at the end of the siphon tubes. 



Animal long and worm-like, living in wood which it rap- 

 idly destroys, doing great damage to ships and wharves. 



^ Height :j greater than length of the shell 4, 5. 



* Height about equal to the length of the shell. (A.) 



A. Length 6 or more 1-3. 



A. Length 4 or less 6. 



1. Teredo navalis, h. (Figs. 18-20). Length and height of 

 valves equal ; posterior auricle expanded, extending much below 

 the anterior one which is small ; pallets rounded on one side, flat 

 on the other, notched at the end ; the stalk about equal to the 

 blade in length. Shell L. 6 ; H. 6 : Pallet L. 6 ; W. 2. Stalk 

 2J. — Massachusetts and south. Very common. 



2. Teredo megotara, Hani, Length and height of valves about 

 equal-; posterior auricle large and separated from the umbo by 



