198 liiiibli' Molliiscii i>j llw ()ri\i:^(ni Coast 



ZDci 1)111 no acli\il\ ni ilie laltrr. I iisiirticieiil obscrx'atioii thnni^ii 

 the vear render^ iiupussihle an asscrlion, at tlii> lime, regarding 

 the s])a\\ning seaMin of this s])ccies on the ( )regon coast (Fig- 

 ure \ 1 , 1 , 2, 3 ). 



7. v^axidoinus giganteus Deshayes. 



The spawning period of tliis species has not been I'uH}- deter- 

 mined tor the Oregon coast. Sections of the ovaries prepared in 

 March. |unc and .\oveml)er show Httle (hfference in the develop- 

 ment of the o\'a. Spermatozoa have been found to be fully 

 formed in March, June and November but in no case have I 

 observed them in an active condition. A closer examination 

 throughout the _\ear will be necessar\- to make a positive state- 

 ment regarding the spawning season of this species. 



The ova of Saxidomus are characterized 1)}' a very thick 

 membrane which envelops each egg. and the large amount of 

 connective tissue separating the follicles of the ovary are also 

 distinctive features. The spermatozoa are elongate, curved, simi- 

 lar to those of l'aph}a staminea (Figure \'I. 4. 5. (k /). 



8. ^lacoma nasuta Conrad. 



The spermatozoa of this species are mature and active during 

 the latter part of March on the Oregon coast. Sections of the 

 ovaries at this time indicate, however, a considerable number of 

 immature ova. Spawning probaljly <jccurs in the late spring or 

 earl\- summer months (Figure \I. 8. 9). 



Q. Mytilus edulis I^innaeus. 



On March 23th. at \'a(|uina l!ay, the mantles of this species 

 were found to be well hlled with fully develoi)ed spermatozoa 

 none of which, however, were in an active condition. Ova at 

 this time were immature. Examination of the species at Sunset 

 liay on September 23rd indicated that the spawning season had 

 just passed. At this time the bodies and mantles of the mussels 

 were very soft and watery being in a spent condition. In both of 

 these instances the specimens were taken from localities with 

 exposure to the ojkmi ocean. The evidence seems to indicate that 



