TIIK MAHINE ALG.E OF NEW ENGLAND. 149 



On rocks at low-waior mark. 

 Common from New York northwartl. 



The coininon Irish moss Avliirli is iisiul lor ciilinaiy imrposos, and also for claiifyin<» 

 hoer. It is also sai«l to be used in the nianufactnie of clu'a[» cotton cloths. Althongh 

 very variable in shape, it is not likely to be mistaken for any other species, except 

 l)Ossibly sterile specimens of (ihiartiua luumiUans or Gymnogongrus Korrcgicus, which 

 is, lujwover, a rare species. \Vhen <;ro\vin^ exposed to the li^^ht, the color is a yel- 

 low-green. 



Suborder IUIODYMENIE.E. 



Fronds nR'niluanaceous or lilironn, solid or tubular; antlicridia lorui- 

 iuLi' supcrlicial patches; tetraspores trii)artite, cruciate, or zouate, either 

 scattered in distinct spots or sometimes sunk in crypts ; cystocarps ex- 

 ternal, eontainiu<i" densely packed subdichotomous lilaments, arranged 

 in distinct masses around a basal placenta with a thick pericarp, which 

 is connected by numerous filaments with the placenta. 



The present snborder is exceedingly ill-defmed, and uo two writers agree exactly as 

 to its limits. In the typical genera we find a distinct basal idaceuta on which are 

 Itorne masses of spores, which when young are seen to bo formed of subdichotomous 

 lilaments, but which when mature arc arranged without order and held together by a 

 uelatinous envelope. Diverging from the type, we have genera like Cordyledadia, iu 

 which, even at maturity, the spores preserve to a certain extent a moniliform arrange- 

 ment, and we then have a cystocarp but little ditlerent from that of Gracilaria, which 

 belongs to the SjyharococcoUka'. On the other hand, we have the order connected with 

 I lie CrifpionemU'w by Chrysgrnenia, which is now placed by Agardli in the lihodymeuiacecp. 

 Ihe position of liliodojjhyUis and Euihora is doubtful. Here we have no distinct basal 

 ]'lacenta, but rather a central placenta or carpogenic cell, reminding one somewhat of 

 I he genus llhahdoma and its allies, which have been included in the Solieriece. Euihora, 

 at any rate, demands a more accurate study, and our own species of llhodophylUs, li. 

 reprccula, does not well correspond with the typical members of the suborder in rela- 

 tion to its cystocarpic fruit. Lomentaria and Champxa agree with the Fhodymcukw in 

 tlieir fruit, although the fronds are peculiar, and we have kept them as a division of 

 the present. 



Tribe I. IvnoDYMENiEyE proper. 



Cystocarps with a basal placenta, fronds solid. 



Fronds dichotomous or palmate lihodymenia, 



lYonds ]>innately compound Plocamhou. 



Fronds liliform ( 'ordylccladia, 



1 Tribe II. RnoDOPnYLLE^i^. 



Cy.stocarps with a central placenta, fronds membranaceous. 



Tetra.si)ores zonate, fronds dichotomous or pinnate IxhodopJnjUis. 



Tctraspores cruciate, fronds dentato-pinnate Kuthora. 



Tribe III. Lomentarie.e. 



Cjstocaii^s with a basal placenta, fronds tubular. 



Fronds constricted at the joints, but with no proper diaphragms, tctra- 

 spores sunk in depressions of the frond Jjomcntaria. 



Fronds with numerous diaphragms, tetraspores superficial.... C/mw?^>/a. 



