16 . SMITHSONIAN CONTRIBUTIONS TO THE MARINE SCIENCES 



conceptacle 



spore 



280 |jm 



FIGURE 10. Clath)x>ii!orphuni coinpactitni conceptacle and sporangial formation. (A) Di- 

 mensional and cellular development of average bisporic conceptacle in southern Labrador 

 relative to season and vegetative tissue. Numbers to the right are averages and can vary with 

 region of development. (B) Sporangial development with time in northern Labrador. In the 

 Gulf of Maine, because of higher vegetative growth rates, this process occurs from October 

 to January. 



Reproduction in Clathromorphum nereostratum 



A detailed developmental analysis of reproduction in 

 C. nereostratum is not available and would require a set of 

 specimens taken in the Aleutian Islands throughout the autumn. 

 Nevertheless, the photographic images published by Lebednik 

 (1976) are adequate to show that the pattern is similar enough 

 to that of C. compactum to allow the use of Figure 8 (developed 

 for Gulf of Maine populations) but not Figure 10 (developed 



for Labrador). However, there are a number of additional dif- 

 ferences that are critical to interpretation for climate archiving. 



Of the 26 specimens of C. nereostratum examined from the 

 Aleutian Islands, 24 were collected in summer (June-August) 

 and 2 in December. Of the 24 specimens collected during the 

 summer, 2 had single-pored gametangial conceptacles at their 

 surface. One of these two plants had mature fertilized female 

 conceptacles (carposporangial conceptacles), whereas the other 

 had postprime male conceptacles with open pores remaining. 



