sufficient care. My results differ from all oi' tJiese. 

 Unfortunately the first tv/o do not state the species on 

 which they worked, and so I cannot state that where my 

 observations differ from theirs, they were in error, though 

 there is such great uniformity of organization in the va- 

 rious species, that we may expect only differences in de- 

 tail in the variou.s types. 



My observations have been based chiefly on Kylatrya 

 f imbriata , Jeffreys , and unless otherwise stated, this is 

 the form described and figured. Specimens of this species 

 I have had in all staces of development from the nev/ly at- 

 tached larva to tlie adult. I have also studied Teredo noi*- 

 vegica, Spengler, and T. navalis, Tanne and vAhere these 

 are essentially different or more favorable for descrip- 

 tion, they have been used. In general, where "Teredo" is 

 used as a popular term, it applies to Xylatryaas well as 

 to the species of Teredo, in a strict sense. 



The object of my study of the "Ship-worms" has been 

 tv^o-fold. In the first place, I have endeavored, by the 

 use of modern methods, to give a detailed account of the 

 organization of this highly specialized Lamellibranch and 

 to correct the errors that have heretofore existed in the 



