C'luptoptcnis Variopt'datiis. 507 



does not include an incompletely formed horizontal extension of two 

 and one-half centimeters. The annelid itself was nearly five centi- 

 meters long'. Likewise, among the larger tnbes, one that has not 

 been recently enlarged by a lateral extension may contain an annelid 

 of greater length and with a larger number of segments than another 

 tube M'hose length is greater as a result of such extension. 



Size at Maturity. — The smallest specimen in which I found ripe 

 sexual products was the second indiA'idual mentioned in the previous 

 paragraph. I am unable to say whether it is a belated individual 

 that was hatched late in the previous season, or one of the precocious 

 individuals of the same season. However that may be, I found 

 three specimens (jSTo. 88, ]^^o. 89, Xo. 90) during the first week in 

 September, 1905, which were about five centimeters long before 

 the lateral extensions were made. They had twenty-five sexual seg- 

 ments, the foremost of which were filled with ripe sexual products 

 as was proven by artificial fertilization of the eggs of the single 

 female with sperm from each of the males. The tubes bore inter- 

 mediate arms that contained no sand and were very recently aban- 

 doned in the formation of lateral extensions that more than doubled 

 their length. (See photograph of Xo. 89, Fig. 2.) That the largest 

 worms were found filled with ripe sexual products so early as the 

 middle of June, makes it possible that at least these specimens could 

 have grown from eggs and reached maturity in the same season. 

 The development and transformation of the larvse and the rapid 

 growth of the young worms in aquaria, in spite of a deficient supply 

 of food, confirms the belief that the young worms may, under favor- 

 able conditions, reach sexual maturity in the same season. Those 

 which are developed later in the same season reach maturity during 

 the following summer. 



Laying of the Eggs. 



The individuals of both sexes are found on the same shoals, and 

 usually from one to three meters apart. The females are more 

 abundant, and constitute sixty per cent of the individuals collected. 

 This association of the sexes w^arrants the fertilization of a large 

 proportion of the eggs as they are swept about in the currents over 



