42 THE AMERICAN ARBACIA 



Hole and localities noted in which Arbacia and other Echinoderms 

 occurred. It was found in a later report (Sumner, Osburn, and Cole, 

 191 1 ) that Arbacia which had been abundant in the summer of 1903 

 were scarce after the severe winter of 1903- 1904, in the summers of 

 1904 and 1905, and were not abundant for several years; in the sum- 

 mers of 1908 and 1909 large quantities were again obtained in Vine- 

 yard Sound. The following table is taken from the more complete table 

 of Sumner, Osburn and Cole (191 1, p. 114). The numbers in the first 

 column are station designations (I.e., p. 201). 



In 1905, throughout Vineyard Sound as a whole, living Arbacia were 

 taken only five times during the summer and never more than two 

 at one time. Strongylocentrotus drobachiensis and Echinarachnius parma were 

 not similarly affected at this time (I.e., p. 115). 



In the summer of 191 1, there was again a dearth o^ Arbacia (Morse, 

 19 1 2). They were particularly abundant in the summer of 19 17, being 

 taken at Kettle Cove, Quisset, North Falmouth, and off Nobska 

 (Allee, 1919, 1923c). But in 19 18, following the severe winter of 191 7- 

 1918, only a few were taken. They had recovered by 1920 (Allee, 

 1923 a, c). The scarcity in 1949, however, followed a very mild winter, 

 but the previous winter had been severe. 



The earliest indication of any decrease in the numbers o{ Arbacia was 

 made by Loeb as far back as 1900 when he says "The sea urchins have 

 practically died out in the immediate neighborhood of the Woods 

 Hole laboratory, and we have to send out the steam launch to collect 

 them. For this reason even at the height of the spawning season there 

 is little danger of the sea water containing spermatozoa in such quanti- 

 ties as to interfere with experiments with unfertilized eggs (Loeb 1900 a, 

 p. 450)." 



A similar disappearance of the British sea urchin. Echinus esculentus, 

 was noted in the deep water of Plymouth Sound (120 ft.) in 1899 after 

 a south-west gale (MacBride, 1906, p. 504). Psammechinus miliaris dis- 



