224 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



The possibility that a species might possess plants some 

 of which were monostromatic while others were distromatic, 

 or that one plant might be monostromatic in one part and 

 distromatic in the other, and this distromatic nature not due 

 to reproductive division, was evidently not considered by 

 Kjellman when he divided the genus Porfhyra into Por- 

 ■phyi'a proper and Diplodei'ma. Not only do we meet 

 monostromatic and distromatic forms in P. abyssicola, but 

 P. miniata and P. tenuissima also exhibit this character in 

 a greater or less degree. It therefore seems to the writer 

 unwarranted to separate such closely allied species by a 

 criterion which does not hold true in all cases; and he fully 

 concurs in the action of Rosenvinge, who, after finding 

 many intermediary forms, reunited the two subgenera. 

 But the writer cannot agree with Rosenvinge in uniting P. 

 fniniata, P. amplissima, P. temiissima, and P. abyssicola 

 under Porphyra miniata, since there exist too many char- 

 acteristic differences, of which the difference in the number 

 of antheridia is but one. The advantage of having but one 

 genus is not only exemplified in the miniata group, but is 

 also shown in others. Not only are several distromatic spe- 

 cies monostromatic during some part of their existence, but 

 all monostromatic species become practically distromatic 

 when in fruit. Besides, the monostromatic nature of the 

 frond does not alter the external appearance by which 

 we can always readily recognize a member of the genus 

 Porphyra. 



Sporocarps. — The formation of the sporocarps of P. 

 abyssicola is apparently identical with that of the carpospores 

 of P. 'miniata, so that, when ripe, each sporocarp contains 

 four carpospores (PL XXII, fig. 23). 



Antheridia. — Like the sporocarps, the antheridia of P. 

 abyssicola agree entirely with those of P. miniata, each an- 

 theridium containing when ripe eight antherozoids (PI. 

 XXII, fig. 25). 



Habitat. — On Zoster a; also on rocks (fide Kjellman). 



Distribution. — As yet known on the Pacific Coast from 

 but a single locality (48° 10' N. lat.). 



