1918 Bovard and Osterud; on Embryological Material 131 



products. A number of mature females were obtained near Turn Island 

 thruout the month of July, 1918. 



Strongylocentrotus purpuratus Stimpson. Rare specimens now found 

 on reefs near Friday Harbor, formerly quite common. Occasionally indi- 

 viduals will be found with ripe eggs or sperms, but for the most part thej 

 are spent before June. 



Echinarachnius excentricus Eschscholtz. Common forms found in 

 sand at False Bay. By July 7, 1917, and July 7, 1918, these forms were 

 quite spent. 



Cucumaria joponica Semper. Abundant along shore among the rocks, 

 and at low tide. Eggs taken in the early part of the season, altho ap- 

 parently ripe, failed to develop when fertilized. The probability is that 

 their season was just coming on. The eggs are small and opaqne. 



Cucumaria chronhjelmi Theil. Abundant along shore and in hauls 

 by the trawl, specially in the mud of East Sound. The eggs are small, 

 greenish and opaque. No development was obtained during the June to 

 August session altho eggs and sperms apparently ripe were found. The 

 season probably came later. 



Leptosyriapta inhaerens (O. F. Mtiller) Verrill. Abundant at False 

 Bay. The phases of reproduction passed early in the summer. No ripe 

 eggs could be obtained by July 7, 1918. 



Stichopus californicus (Stimpson) Edwards. Abundant forms in 

 shallow water near the Station, and by trawling. The eggs are large, 

 translucent and colored a delicate pinkish cream. No developing larvae 

 have been obtained, but the indications are that the season for this holo- 

 thurian is later rather than earlier. By July 15, 1918, individuals were 

 found yielding well formed eggs which discharged freely from the torn 

 ovaries. Owing to the size and clearness of the eggs, the development of 

 this must be a wonderful sight. Fertilization was obtained with these 

 eggs. Cleavage did not begin for five hours after the addition of sperms, 

 and but few developed further than the 1-celled stage. Either the eggs 

 or the sperm may not have been mature. Careful observation should be 

 made on these forms as the indications are that good embryological ma- 

 terial may be found in this holothurian. 



The following starfish had passed their season (1917): Pisaster 

 ochraceus (Brand) A. Agassiz, Luidia foliolata Grube, Leptasterias hex- 

 actis (Stimpson) Verrill, Pycnopodia helianthroides (Brand) Stimpson, 

 Dermasterias imbricata (Grube) Perrier, and Pteraster tesselatus Ives. 

 However, judging from the voluntary extrusion of sperms from the males 

 of Piasaster and Luidia, the season may have been on shortly before the 

 Station opened. In former years Leptasterias has been known to begin 



