132 Pub. Puget Sound Biol. Sta. Vol. 2, No. 42 



development the latter part of February, with completion in April or early 

 May.' 



MoUusca 



Saxidomus giganteus Deshayes. Common on beaches at low tide. 

 Ripe eggs and motile sperms were seen by Professor Trevor Kincaid dur- 

 ing the first week of July, 1918. Pecten larvae were found in tow on 

 July 1, 1918. 



Mya arenaria Linnaeus. Common mud clam fund in sand and mud 

 of nearby beaches. The eggs and motile sperms may be obtained from 

 torn gonads. 



Mytilus edulis Linnaeus. Common mussel found on rocks and piles. 

 The eggs and active sperms are easily obtained from torn gonads. 



No marked activity of the gonads was noted in Marcia, Paphia, En- 

 lodesma, Macoma, Monia, or Cardium; so these were considered out of 

 season (1917). 



Lacuna porrecta Carpenter. A very abundant mollusk with wide dis- 

 tribution, living on kelps and eelgrass. The eggs are doughnut-shaped and 

 may be obtained in all stages of development thruout the season. 



Haminea vesicula Gould. Abundant at low tide among the Ulva and 

 eelgrass. The height of the reproductive season is July and August. Com- 

 mon on the beaches at Brown Island and Newhall's Beach. The egg masses 

 are 12-38 mm. in height, and are whitish balloon-shaped bodies, with num- 

 erous eggs enclosed in a gelatinous substance. These may be anchored in 

 mud or on eelgrass. The masses are best collected between five and nine 

 o'clock in the morning, to obtain the earliest cleavage stages ; for the mol- 

 lusks seldom are found laying after the early morning hours. The habits 

 of this animal are well described by Leonard.^ 



Thais lamellosa Gmelin. A very abundant mollusk found on the 

 rocks at low tide everywhere. The egg capsules are commonly called 

 "Sea Oats." The height of their season is before the station opens, the 

 last of June; but belated individuals have been found depositing their 

 capsules of eggs as late as July 7 (1918). For the most part, by June 

 the capsules will be found empty or the embryo in very advanced stages. 



Argobuccinum oregonense Redfield. A very common mollusk found 

 Ln reefs. The eggs in all stages of development may be obtained from 

 June to August. It is one of the best sources of embryological material 

 because of the abundance, accessibility, and ease with which the animals 

 may be raised in the laboratory. Care must be exercised in removing cap- 

 sules from the rocks, so as not to rupture them, for unfortunately develop- 



1 Osterud, H. L. Preliminary observations on the development of Leptasterias hexactis. Pub. 

 Puget Sound Biol. Sta. Vol. 2, pp. 1-15. 1918. 



= Leonard, Ruth. Early development of Haminea. Pub. Puget Sound Biol. Sta. Vol. 2, pp. 

 45-63. 1918. 



