FRKSH-W ATKK ALQ.E OF TUB UNITED STATES. 141 



latis, rotundatis vel sinuato-l.i- trit-renatis ; lobo polari abbrcviato lute truncate, levitcr cmar- 

 giuuto, anguli.-. ueutis laterulitcr plus minus ponvctis; cytiodvrmate subtilissimc puuctato. 



Syn. E. binalf, (TriUMN) UAI.FS, British Dcsmidee, p. 90. 



Jl,i!>. Florida; Bailey. Rhode Island, (S. T. Olncy,) Thwaites. Pennsylvania ; Wood. 



Kri'iid rcry minute, scarcely twice as long as broad, oblong ; segments with their basal portion 

 cither entire. or liierenate ut thu sides, slightly contracted beneath the ends ; ends dilated, not 

 protuberant beyond the angles, its central notch acute, broad; tr. v. with two lateral infla- 



tions, encl-4 truncate, angles rounded. (A.) 



ik. Fig. 3, pi. 13, represents the front view of a frond, magnified 750 



diameters. 



Genus MICRASTERIAS, Ac. (1827). 



ihi- compresssp, |irofonde constrict, a fronto orbiculares vel late ellipticffi, a vcrtice fusiformcs 

 cum utroi|iie polo acuto, semicellulse tri- vel quinquc-lobe ; lobi basalcs aut intcgri aut pluripliciter 

 iiiciMi-lohuluti ; lobus polaris aut integer aut sinuatus ant emarginatus, et interdum angulis produc- 

 tus ct bitidiis. Cytioplasma chlorophyllacca in cellulae lumen subeequalitcr ili.-trilnitii, granula 

 ainylacea sparsa involvena. Cytioderma plerumque la-ve, nonuuuquam punctatum, granulatum vel 

 muiTonatum. 



-porse globosa, aetate provecta aculeis simplicibus, apice bi- multi- fldis, nonnanqnam repetito- 

 multilii'lis armato;. 



M compressed, profoundly constricted, viewed from the front orbicular or broadly elliptic, from 

 the \ertex fusiform with acute ends. Semicells 3- or 5-lobed ; basal lobes either entire or many 

 times incisely-lobulate ; end lobe either entire or sinuate or eraarginate, and sometimes with its angles 

 .'ed and bifid. Chlorophyllona cytioplasm distributed nearly uniformly in the cavity of the 

 cell, surrounding scattered starch granules. Cytioderm mostly smooth; sometimes punctate; 

 granulate or mucronate. 



-pores globose, at maturity armed with simple spines, whose ends bifid or multifid, and somc- 

 repeatedly multi lid. 



A. SemiccUula trilobx. Lobi batalea horizontales ; lobus polaris valde dilalalus, dorxo plane 

 convexus, Iruncatua vel leoiter retusug, a lobin bagalibus ginu amplixximo dixcretus. 



A. Semicells trilobate. Baal lobe horizontal ; end lobe strongly dilated, with the back con- 

 vex, truncate, or slightly refuse. 



JI. nrcnaln. BAILET. 



M. mediocris, quadrangularis, paulo latior qnam longa, profunde pinnatifida; lobis basalibns 

 angustis elongatis, arcuatis, in apiccra acutum attcnuatis, divergentibus; lobis polaribus 

 angustusirais, atrinque graciliter productis, in apicera acutum attenuatis, in medio dorso 

 modice rctusis. (R.) 



Sijn. _ M. arcuata, BAILEY, M-icroscopical Obserrations : Smithsonian Contributions, vol. ii. 



Bab. In stagnis. Florida; Bailey. 



" Quadrangular, segments three-lobod, the basal lobes long and arcuate, subtended by the trans- 

 verse projections from the ends of the slightly notched terminal lobes." (Bailey.) 



HI. eipanM, BAILEY. 



M. mediocris, tain longa qnam lata, lobis stellatim expansis; lobis basalibns angustis in apicem 



acutnm attcnuatis, divergentibus, rectis; lobis polaribus e basi angusta sensim dilatatis, in 



mcdio dorso late sinuatis, angulis acutis (sed muticis). (R.) 



Syn. 3r. expansa, BAILEY, Microscopical Observations : Smithsonian Contributions, vol. ii. 

 Ilab. In stagnis, Florida; Bailey. 



