1922 Klugh,—Polymorphism in Enteromorpha crinita 53 
(e mp 
Surface. 0.07-14.76. Av. 5.65. 
At 11 m. 7.16-20.93. Av. 12.75. 
Average salinity 9.18. 
At this station E. crinita had long monisophonous tips. 
'The data for Station 94, some ten miles from the mouth of the river, 
Was: 
Surface. 0.04-3.37. Av. 2.13. 
At 12 m. 0.07.-17.45. Av. 4.46. 
Average salinity 3.30. 
Here the alga was not as profusely branched as at the preceding 
stations and the monosiphonous tips were very long. 
At Station 96, some twenty miles from the mouth of the river, 
and near the head of the tide, the data was as follows: 
Surface. 0.0-0.42. Av. 0.08. 
At 6 m. 0.0-8.35. Av. 1.67. 
Average salinity 0.87. 
At this station Enteromorpha crinita existed in a form which bore 
very little resemblance to typical examples of this species and which 
would not have been recognized as this species but for two facts 
—Firstly, the examination of material from numerous parts of the 
estuary having revealed the gradual lessening of the tubular branched 
condition and the gradual increase in length of the monosiphonous 
tips, and secondly, the finding of young plants of this species in a 
monosiphonous condition at other stations. In the monosiphonous 
state this species has the appearance of one of the Ulotricaceae rather 
than of the Ulvaceae. 
That salinity and not temperature is the causative factor of this 
polymorphism is shown by an examination of the water temperature 
data, the mean of the average surface and deep temperatures for the 
above stations being: 
Station 76—14.4? C. 
Station 81—16.0° C. 
Station 82—17.2? C. 
Station 94—17.2° C. 
Station 96—16.6? C. 
Thus the temperatures for one of the stations at which E. crinita 
existed in its typical form was almost the same as at the station where 
it was monosiphonous, while it was in its intermediate phase at the 
stations with the highest temperatures. 
