64 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



cept at the apex, formed from the superficial cells 5 fronds covered with 



clusters of hairs ; paraphyses wanting. 



A small genus, containing probably not more than half a dozen good species, which 

 are widely diffused. In the Nereis Am. Bor. the genus is placed by Harvey in the 

 Dictyotacece. That order is now restricted to a group, not represented, as far as is 

 known, on the coast of New England, in which there are quiescent spores, tetraspores, 

 and antheridia, but no zoospores, and Punctaria is evidently related to the Phceosporece, 

 judging by its sporangia. Litosiphon pusillus, a small parasite on various algae, is closely 

 related to Punctaria, but differs in having a filamentous frond and more simple 

 sporangia. It probably occurs on our coast, but has not yet been observed. 



P. latifolia, Grev.; Phyc. Brit., PI. 8; Etudes Phycol., p. 13, PI. 5. 



Fronds pale olive-green, gregarious, shortly stipitate, lanceolate or 

 obovate, four to twelve inches long, one to five inches broad, substance 

 tender. 



Var. zoster^e, Le Jol. (P. tenuissima, Phyc. Brit., PI. 248.) 



Fronds thin, pale, lanceolate at both extremities, narrow, margin un- 

 dulated. 



On different algae at and below low- water mark. Spring and summer. 

 Europe. 



P. plantaginea, (Roth) Grev. ; Phyc. Brit., PI. 128. PI. IV., Fig. 5. 



Fronds deep brown, gregarious, broadly lanceolate, attenuated at 

 base, one to three inches broad, three inches to a foot long, substance 

 somewhat coriaceous. 



Orient, L. I.; Point Judith, E. I., Olney; Wood's Holl, Gloucester, 



Mass.; Europe. Summer. 



It is not altogether easy to distinguish our two species in some cases, although as a 

 rule they are sufficiently distinct. P. latifolia is much the more delicate of the two, 

 and has a greenish tinge. When in fruit it is punctate, the dots being the sori. Both 

 forms of sporangia are often found simultaneously on the same frond. In P. planta- 

 ginea the frond is decidedly brown and rather coriaceous, and the punctate spots are 

 caused by the dense clusters of hairs which are often found to correspond on both 

 sides of the frond. Both species are common in spring and summer, and although 

 often washed ashore in considerable quantities on exposed beaches, they prefer quiet 

 bays. , » 



Family DESMARESTIE^E. 



Fronds branching, cylindrical or compressed, with an axis of fila- 

 ments composed of elongated cells and a cortex composed of spheroidal 

 cells 5 unilocular sporangia formed by the direct transformation of the 

 cortical cells; plurilocular sporangia unknown. 



DESMARESTIA, Lamx. 



(In honor of J. G. Desmarcst, a French naturalist.) 

 Fronds olive-brown, solid, cylindrical or compressed.^ much branched, 

 attached by a disk, cortical layer composed of small polygonal cells, 



