THE TEREDO AND ITS DEPREDATIONS. 545 



"fine lady" wear in the future if the prince of precious stones should 

 follow the example of those standing closest to its throne, and allow 

 itself to be reproduced for a few shillings ? 







THE TEEEDO AND ITS DEPREDATIONS. 1 



By Dr. E. H. VON BAUMHAUER, 



COMMISSIONER TO THE CENTENNIAL EXHIBITION FROM HOLLAND. 



II. 



CONTRARY to the opinion of Sellius, who regarded the teredos as 

 hermaphrodites, Quatrefages has taught us that they are of both 

 sexes and that the ratio of males to females is about one to twenty. 

 The females are oviparous. The eggs are expelled by the branchial 

 siphon : Quatrefages found them in that siphon and in the branchial 

 canal itself. The mode of fecundation is, however, unknown ; it is sup- 

 posed that, in that act, two different teredos project their siphons and 

 bring them in contact. 



As regards the metamorphoses which the eggs undergo, either in 

 the branchial tubes or in the water, nothing has been added to what 

 was made known through the researches of Quatrefages in 1849. That 

 naturalist has taught us that the eggs pass through the series of modi- 

 fications, from the starting-point, which one meets with in the examina- 

 tion of all animals i. e., the formation of the germinative area and of 

 the vesicle of Purkinje, the disappearance of this and the breaking up 

 of the vitellus. The eggs undergo their development in the branchial 

 cavity of the mother; the embryos resemble very small, rounded ani- 

 malcula of vesicular form, and are provided with vibratile cilia, by the 

 aid of which they have regular movements, and probably are expelled 

 from the branchial cavity into the siphon. In a third phase of devel- 

 opment the bivalve shell is formed, the foot appears on the outside, 

 the vibratile cilia form a sort of crown, and the embryo thus possesses 

 the faculty of locomotion as well by creeping as by swimming. The 

 development of the eggs takes place from time to time, and especial- 

 ly in the month of June, although even as late as the 29th of July 

 Harting found eggs in all the teredos which he opened. The devel- 

 opment of the eggs progresses very rapidly ; in four days they pass out 

 of the embryonic state, fully equipped for living in wood. Toward the 

 end of June, Kater observed them in large numbers on the surface 

 of wood, and by the 15th of July he found them in the interior in the 

 form of perfectly-developed teredos. Even in the month of December, 

 but no later, he saw young teredos enter into pieces of wood placed by 



1 Extract from the "Archives of Holland," vol. i., translated by Edward R. Andrews. 

 VOL. XIII. 3fi 



