468 



MARINE FUNGI 



perithecia, but thev are otherwise quite normal, although Ulva 

 does not fruit. 



Sutherland (1915) regards Mycosphaerella pehetiae as a symb- 

 biont with Pelvetia. In this case the perithecia and the host con- 

 ceptacles mature coincidentallv. 



Didymella conchae is of particular interest because of its ability 

 to decalcify the shells of certain limpets, molluscs, and barnacles, 



Fig. 80. Gu'ignardia ulvae on Ulva califoriiica. (After Reed.) A. Habit 

 sketch, indicating swollen areas in which the perithecia are embedded. B. 

 Section of thallus and perithecium. C. Ascus of G. ulvae. D. Ascospores. 



E. Germination of ascospores. 



including Acmea digitalis, A. fene strata, A. limatula, A. pelt at a, A. 

 scabra, A. scutum, Balamis glandulosa, Littorina planacis, Mitella 

 polyvierns, and Tegula fwiebralis [Bonar (1931)]. 



If further acquaintance with this group is sought, it may be 

 obtained by study of the species assembled in Table 32. This list, 

 however, does not include all the Ascomycetes found on marine 

 algae and seed plants. 



MARINE FUNGI IMPERFECTI 



Know ledge of these fungi, which is limited to a few saprophytic 

 species, has come from direct examination of decaying algae and 



