ARCELLINA. 



[ 60 



ARCYRIA. 



arid interesting. They agree exactly with 

 those upon the valves of the Diatomaceae in 

 regard to the requirements for their display; 

 with unilateral oblique light, lines only are 

 visible. Their true structure resembles that in 

 PI. 11. fig. 48, or PI. 13. fig. 29, except that 

 the rows are somewhat wavy or even spiral. 

 Aquatic; breadth 1-500 to 1-200". In the 

 young state it is very transparent and pale, 

 and the markings are with difficulty distin- 

 guished. PI. 25. fig. 24. represents the ani- 

 mal with its processes protruding from the 

 carapace. 



We have seen two of these animals con- 

 jugating and so firmly united by the soft in- 

 ternal substance, that they were not separable 

 by rolling them over between two plates of 

 glass. 



2. A. aculeata (PI. 23. fig. 14 b). Carapace 

 brownish, discoidal, convex above, with one 

 or more irregular spinous prolongations at 

 the margin ; aquatic; breadth 1-200" without 

 the spines. 



3. A. dentata (PI. 23. fig. 14 c). Hemi- 

 spherical, anguloso - polygonal ; carapace 

 membranous, homogeneous, yellowish or 

 greenish ; aquatic ; breadth 1-560 to 1-200". 



4. A. aureola (Cyphidium aureolum, Ehr.). 

 (PI. 23. f. 38). Carapace yellow, angular, 

 with numerous tubercles, four of which are 

 larger and more projecting; a single expan- 

 sion of varied size ; breadth 1-560 to 1-420 "5 

 aquatic. Fig. 38 a represents the carapace 

 viewed from above, b the same supported 

 upon one angle, and the single expan- 

 sion. 



BIBL. Ehrenberg, Infusionsth.-, Dujardin, 

 Infusoires. 



ARCELLINA, Ehr. A family of Infu- 

 soria. 



Char. Animals contained in a univalve 

 carapace, of an urceolate or shield- like form, 

 with a single orifice from which one or more 

 irregular and variable expansions are pro- 

 truded, which form the organs of locomo- 

 tion. 



The substance of the body resembles that 

 of an Amoeba. 



Dujardin places this family among the 

 Rhizopoda. 



Genera : Arcella (including Cyphidium, 

 Ehr.) and Difflugia (including Trinema, 

 Din.). 



See SPIRILLINA. 



ARCHEGOT^IUM. Also called pistilli- 

 dium. The rudimentary organ representing 

 the ovule in the higher Flowerless Plants, 

 such as Mosses, Ferns, &c. (excluding the 



Thallophytes). These organs are more mi- 

 nutely described under the heads of the va- 

 rious Classes, in speaking of their reproduc- 

 tion. 



In the Mosses and Liverworts they are 

 flask-like cellular bodies, found in terminal 

 or axillary buds on the leafy stems (figs. 32 



Fig. 32. Fig. 33. 



Archegonia of Mosses. 

 Magnified 50 diameters. 



& 33). In the Ferns and Equiseta they are 

 produced on the prothallium, after the ger- 

 mination of the spores. In the Lycopodiaceae 

 and Marsileacere they are produced upon the 

 cellular plate, representing a prothallium, de- 

 veloped in the large spores when these be- 

 gin to germinate. The corpuscula of the 

 Coniferae are analogous bodies to the last. 

 See HEPATICACE^E, MUSCACE.E, FILICA- 



CE^E, EftUISETACE^E, LYCOPODIACE^, 



MARSILEACE^E, also CONIFERS and CHA- 



RACE.E. 



ARCHIDIUM, Brid. A genus of Bru- 

 chiaceae (Acrocarpous Mosses), including 

 some of the Phasca of Linnaeus, &c. 



A. phascoides, Brid.= Phascum alternifo- 

 lium, Hook, and Taylor. 



ARCYRIA, Hill. A genus of Myxogas- 

 tres (Gasteromycetous Fungi), growing on 

 rotten wood, with bright-coloured spores 

 and filaments. The elastic filaments of the 

 capillitium have no spiral fibres, but are a 

 little tuberculated. Species : 



1. A. punicea, Pers. Common; spores 

 and capillitium purplish vermilion. Grev., 

 Sc. Crypt. Flora, t. 130. 



2. A. incarnata, Pers. Not uncommon ; 

 smaller, with a shorter stipe and with flesh- 

 coloured spores and capillitium. 



3. A. cinerea, Bull. Spores and capil- 

 litium cinereous. 



4. A. nutans, Bull. Spores and capil- 

 litium dirty-yellow ; capillitium nodding. 

 Trichia nutans, Sowerby, t. 260; Arcyria 



flava, Grev., Sc. Crypt. Fl. t. 30.9. 



5. A. umbrina, Schum. Spores and 



