132 TEREDINIDJE. 



distinct apertures_, for the passage of the siphons. 

 Quatrefages^ too^, extracted specimens of T. pedicellata 

 from their cases^ and kept them alive in sea-water for 

 more than fifteen days. Experiments tried by Selliu 

 in putting Teredines into rain-water^ beer^ milk^ and 

 similar fluids resulted (as might have been expected) in 

 their becoming feeble^, and ultimately in their death. 

 The fecundity of the Teredo next attracted the atten- 

 tion of its biographer. He computed that the eggs 

 contained in a portion of one ovary were 1^874^000 (a 

 number exceeding the then population of the eight 

 chief cities of Christendom^ namely London, Paris, 

 Amsterdam, Venice, Rome, Dublin, Bristol, and Rouen), 

 and that the entire ovary contained nearly seven times 

 as many, and considerably exceeded the population of 

 the seven United Provinces and all Great Britain to 

 boot. He minutely described the ova and fry, which 

 latter he found in different parts of the body. But 

 Quatrefages has recently investigated this branch of the 

 subject with very great care, aided by the light of 

 modern science ; and the result of these investigations 

 will be given in the proper place. The knowledge of 

 comparative anatomy possessed by Sellius was of course 

 somewhat imperfect. Perhaps the phrase which he 

 used in describing the ovary, ^^ materia formatrix 

 ovulorum," is not recognized by physiologists of the 

 present day ; at any rate it is intelligible. Deshayes 

 has pointed out two or three more errors of this kind ; 

 but certain modern naturalists, whose opportunities 

 were far greater than those which Sellius enjoyed, have 

 committed mistakes of a not less grave character. I 

 need only allude to the published accounts of the 

 organization of Dentalium, as an instance of such inac- 

 curacies. Sellius goes on to say that the sheath is 



