lidiblc Moilnsca of the Orci^uii Coasl 195 



ity. (Jn March 29th, 19 19, however, both male and female clams 

 were in a spent condition. There is probably some variation in 

 the dnration of the spawning season from year to year and, no 

 doubt, a like variation under different conditions. My observa- 

 tions were made at Newport, Oregon, where the clams were 

 taken from the protected tide flats of the Vaquina River. 



The examination of males on Jul}- 31st did not reveal the 

 presence of formed spermatozoa. It is tpiite clear that there is 

 no summer spawning of this species on the Oregon coast. In 

 September 1918, small clams about 50 mm. in length were quite 

 abundant in the gravel beds of Xetarts Hay. Although the rate 

 of growth of Schizothaerus nuttalli has not been determined, it is 

 verv probable that these small clams may have resulted from the 

 sj^awn of the i)revious spring. 



3. Paphia staiuinea (Conrad). 



There is some evidence to believe that the "little neck clam" 

 has both a spring and a late summer spawning season on the 

 Oregon coast. Examinations made at Newport on March 30th 

 revealed ova and spermatozioa apparently in a state of maturity, 

 the latter very active (Figure V, 7, 8, 9). The condition of the 

 bodies of both males and females indicated that the spawning 

 period was approaching. On September 22nd of the same year 

 the species was examined at Coos lUiy and found to be in a con- 

 dition identical with that observed at Newport in .March. The 

 ova were to all appearances fully matured and the spermatozoa 

 were very active. 



( )n July 31st, 1918, well formed spermatozoa were found in 

 this species at Netarts Bay but they were in a resting condition. 

 I have not examined the species at Newport in September or at 

 Coos 15ay in March. In both localities, however, the clams were 

 taken within protected bays and the variance in temperature of 

 the two places cannot be great. It would appear, therefore, from 

 our present incomjilete knowledge, that Paphya staminea may 

 s]jawn in both the spring and late summer seasons on this coast. 



4. Mya arenaria Linnaeus. 



The reproductive organs of this clam have been examined 



[ 10 1 



