158 



ALG.fc. 



cation : opaque seeds imbedded in distinct receptacles and 

 finally escaping by superficial pores. — (None of the Irish 

 genera have distinct leaves.) 



1. Cystoseira. Vesicles simple, innate in the branches. 

 Receptacles small. Seeds in distinct cells. 



2. Halidrys. Vesicles stalked, lanceolate, divided by trans- 

 verse septa. 



3. Fucus. Vesicles (when present) simple, immersed in the 

 frond. Receptacles turgid, containing tubercles imbedded in 

 mucus. 



4. Himanthalia. Frond cup-shaped. Receptacles (frond- 

 like) very long, dichotomously branched, strap-shaped. 



Tribe II. Lichine.e. Pla?its cartilaginous, fiat, branched, 

 (minute.) Fructification receptacles furnished with a ter- 

 minal pore, containing pellucid seeds disposed in moniliform 

 series. 



5. Lichina. Character the same as the Tribe. 



Tribe III. - Lamina rie.e. Fronds stipitate ; stipes terminat- 

 ing in a foliaceous cleft or entire, occasionally midribbcd ex- 

 pansion. Fruct. obscure. 



6. Alaria. Frond membranaceous, with a cartilaginous 

 percurrent midrib. 



7. Laminaria. Frond simple or cleft, destitute of distinct 

 midrib. 



Tribe IV. Sporochnoide.e. Pfa?its cartilaginous or mem- 

 branaceous, much branched, inarticulate, bearing at some pe- 

 riod of groicth deciduous tufts of bright green filaments. 



8. Desmarestia. Frond plane or compressed, distichously 

 branched, when young furnished with marginal deciduous tufts 

 of fine green filaments, the branches set with marginal spines. 

 Grev. 



9. Dichloria. Frond cjdindrical, filiform, cartilaginous, 

 pinnated with opposite branches, becoming flaccid and of a ver- 

 digris green colour on exposure to the air. Fructification un- 

 known. Grev. 



10. Sporochnus. Frond filiform, cylindrical, or compress- 

 ed, cartilagineo-membranaceous. Fructification : club-shaped, 

 moniliform filaments radiating in scattered warts, or concen- 

 trated in distinct (mostly clavate stalked) receptacles, often ter- 

 minated by a deciduous tuft of filaments. Grev. 



