326 ^ Linruean Society. 



without distinct embryo. He refers to Mr. Brown's memoirs on 

 Rafflesia, and to Mr. Griffith's on the plants referred to Rkizanthece, 

 for instances of inembr5'onal seeds ; and observes that we have no 

 satisfactory evidence of the existence of an embryo, in the ordinary 

 sense of the term, in BurmanniacecE. He notices also the imperfect 

 condition of the embryo in Cuscuta, in Orobancheee and in Monotropa ; 

 and the striking discrepancy between the well-developed cotyle- 

 donous embryo of the leaf-bearing Cacteee and the solid and undi- 

 vided embryo of the leafless genera of that family. Admitting then, 

 in Triuriacece, Bunnanniacece, Balanophoreee, &c., the existence of an 

 organ endowed with the function, but wanting the usual structure, 

 of the embryo, he proposes for this organ the name of protoblastus, 

 with the view of distinguishing between a protohlasteous and a coty- 

 ledonous embryo. Modifications of the protohlasteous structure may 

 occur ; and the author refers to Ceratophyllum and to several genera 

 of Aroideee (especially Cryptocoryne) as furnishing instances of ano- 

 malous forms of embryo, which are best explained by a reference to 

 this view of the subject. He also notices some peculiarities in the 

 structure of the seed of Pistia, which he regards as in some points 

 analogous to that of Sciaphila, although widely different from it in 

 others. 



Setting aside then the Acotyledonous embryo as a character of 

 primary importance, and regarding it only as an imperfect condition 

 • of development, common to all the great divisions of the vegetable 

 kingdom, it is evidently among the Endogens that Triuriacece should 

 take their place, and the author concludes that upon the whole the 

 greatest amount of approximative characters leans towards Fluviales. 

 He then gives the characters of the order and its subdivisions as 

 follows : — 



Triuriace^, jl'/2ers(1841). Triuracese, Gor«f«. (1843). Triuridacese, Zinrf/. 

 (184G). 



Char. Ord. Herhce parvulae, subhyalinse ; rhizomate fibrose, interdum 

 substolonifero ; caule subsimplici, textura cellulosa, vasis deferentibus 

 in axi centralibus ; /o/»"s alternis, bracteiformibus, sessilibus, nervis 

 destitutis. Flores monoici, v. dioici, rariiis polygami, spicati ; pedi- 

 cellis alternis, 1-floris, basi bracteatis. Perianthium in utroqiie sexu 

 3-4-G-8-partitum, hyalinuni, textura celluloso-bullata, v. papilloso- 

 rugosa ; laciniis ovatis, acutis, basi in tubum brevissimuni coalitis, 

 apice inteidum processu elongate donatis, aestivatione valvatis. Sta- 

 mina iiumero varia, pauca, in fundo periantbii fere sessilia, supra andro- 

 pborum scepissime magnum carnosum inserta ; antherce 4-loculares, 

 2-valves, rarius in lobos 2 sejunctse. Ovaria plurima, in gynaecium 

 toro adnaluin densissime aggregata, 1-locularia; ovulo unico, e basi 

 erecto. Stylus excentricus, intrbrsiim lateralis, saepissime fere basilaris, 

 glaber aut plumoso-fimbriatus. Stigma obsoletuni, v. truncato-clavatuni. 

 Carpidia plurima, baccata, excentrica, obovata, stylo persistente fere 

 basilari notata, coriacea et indehiscentia, v. interdum utricularia dorso 

 valvatim debiscentia ; caryopside obovata, tela arillfeformi donata ; 

 tesid ovata, dura, testacea, coloratS, transversim scalariformi-striata. 

 Nucleus (embryo protoblasteus) opalinus, integuniento areolis elongatis 

 reticulate inclusus, textura mollis, cellulosus; cellulis materie oleosA 



