730 MARCH AKTIACE^. (LIVERWORTS.) 



1. D. hirstlta, Nees. Thallus 2-5' long, 6-9" wide, deep green, be- 

 coming blackish, entire on the margins, naked above or with a delicate ap- 

 ■pressed pubescence ; dioecious ; receptacle many-fruited, the margin closely 

 hairy ; peduncle rather long, chaffy at the apex. — On moist calcareous rocks, 

 Easton, Penn. (Porter), and southward. 



8. LUNULARIA, Micheli. (PI. 25.) 



Thallus oblong with rounded lobes, distinctly areolate and porose, with im- 

 bricate sublunate scales beneath ; gemmaj in crescent-shaped receptacles. 

 Diacious. Fertile receptacle usually cruciately divided into 4 horizontal seg- 

 meuts or involucres, which are tubular, vertically bilabiate and 1 -fruited. 

 Calyptra included, persistent. Capsule exserted, 4-8-valved. Elaters short, 

 very slender, mostly free. Spores nearly smooth. Antheridia borne in the 

 apical sinus of the thallus. (Name from lunula, a little moon.) 



L. VULGARIS, Raddi. Thallus 1-2' long, forked, innovating from the 

 apex, with a somewhat diffuse costa; peduncle very hairy, 1-1^' long. — 

 Introduced into greenhouses ; always sterile, but easily recognized by the 

 characteristic receptacles. (L. cruciata, Dumort.) (Int. from Eu.) 



Order 140. RICCIACE.E. 



Plant-body a dicliotomously branching thallus, terrestrial or aquatic. 

 Capsules short-pedicelled, or sessile on the thallus, or immersed in its 

 substance, free or connate with the calyptra, globose, at length ruptur- 

 ing irregularly. Calyptra crowned with a more or less de^ iduous point. 

 Elaters none. Spores usually angular, reticulate or muriculate. An- 

 theridia ovate, immersed in the thaUus in flask-shaped cavities with 

 protruding orifices (ostiules). 



1. Riccia. Capsule immersed in the thallus. Involucre none. 



2. Sphaerocarpus. Capsule sessile on the thallus. Involucre inflated-pjTiform. 



1. RICCIA, Micheli. (PI. 22.) 



Thallus at first radiately divided, the centre often soon decaying ; the divis- 

 ions bifid or di - tri-chotomous, flat or depressed or channelled above, usually 

 convex and naked or squamulose beneath ; margins naked or spinulose-ciliate ; 

 epidermis usually distinct, eporose ; air-cavities evident or wanting. Capsule 

 immersed, sessile. Calyptra with a persistent style. Spores alveolate or mu- 

 riculate, usually flattened and angular. (Named for P. F. Ricci, an Italian 

 nobleman, patron of Micheli.) 



§ 1. LICHENODES. Fruit mostly protuberant above ; spores about %Aix broad, 

 issuing through openings in the upper surface of the thallus ; terrestrial spe- 

 cies [on damp, usually trodden or cultivated ground), without air-cavities. 



* Thallus naked, without cilia or scales. 



1. R. Frostii, Aust. Thallus orbicular, 6- 12" broad, thinnish, grayish- 

 green, the apex and narrowly membranous margins sometimes purplish, mi- 

 nutely pitted ; divisions linear or subspatulate, subtruncate and slightly 

 emarginate ; rootlets smooth or obsoletely papillose Avithin ; capsules very 

 prominent beneath ; spores barely 50 fi broad, nearly round, somewhat mar- 

 gined, with depressed sides when dry, fuscous. — Ohio, 111., and westward. 



