PYCNIDIA. 



[ 649 ] 



PYXICOLA. 



of Infundibulate Cyclostomatous Polyzoa, 

 family Tubuliporidae. 



Char. Zoary erect, cylindrical ; cells half- 

 immersed, arranged on all sides 5 orifices 

 prominent. 



Two British species P. proboscidea, and 

 P. deflexa. The latter common on shells 

 from deep water. 



BIBL. Johnston, Br. Zooph. 278 ; Gosse, 

 Mar. Zool. ii. 8. 



PYCNIDIA. A term applied to the 

 receptacles enclosing stylospores in the 

 LICHENS and FUNGI. 



PYCNOG'OXUM. A genus of Podo- 

 somata, Sea Spiders, which are usually 

 placed amongst the Crustacea, but by some 

 authors amongst the Arachnida. They have 

 no special respiratory organs, and only four 

 pairs of legs. They sprawl over seaweed, 

 and hide under stones. There is a pair of 

 chelate mandibles. 



PYCXOPHY'CUS, Kiitz. A genus of 

 Fucaceae (Fucoid Algae), containing one 

 British species, P. (Fucus) tuber culatus; re- 

 moved from Fucus on account of its cylin- 

 drical frond, the compact cellular substance 

 of the receptacles, and the ramified fibrous 

 pseudo-root. The fructifications, formed at 

 the ends of the dichotomous lobes of the 

 frond, are elongate, cylindrical, more or less 

 tuberculated, and with numerous pores 

 opening from conceptacles containing spore- 

 sacs and antheridia (together), resembling 

 in general those of Fucus. The spore-sacs 

 are collected at the bottom of the concep- 

 tacles, the antheridia at the upper part. 

 See Fucus. 



BIBL. Harvey, Mar. Alg. 18 ; Phyc. Br. 

 89 ; Decaisne and Thuret, Ann. Sc. N. 3. 

 iii. 5 ; Thuret, ibid. xvi. 10. 



PYGED'IUM. The last segment of the 

 abdomen of certain insects. It exhibits a 

 curious structure in Pulex (p. 647) ; the 

 same is stated to occur also in Chrysopa, 

 the lace-winged fly, the locust &c. (Davis. 

 Jn. Mic. Soc. 1879, ii. 252.) 



PYRAMID'IUM, Bridel. A genus of 

 Funariaceae (Acrocarpous Mosses), allied to 

 Funaria in habit, but differing in important 

 points. 



Pyramidium tetragonum, Brid. = Gymno- 

 stomum tetragonum, Schwagr. 



PYRENID'lUM, Nyl. A genus of Col- 

 lemaceous Lichens. 



Char. Thallus minute, stellato-divided ; 

 apothecia pyrenocarpous, verrucarioid. P. 

 actinellum ; on chalk. (Leighton, Lick. Fl. 

 36.) 



PYREXODEL A series of Lichenacei. 



Char. Fructification in closed receptacles. 



BIBL. Leighton, Lich. Flora, p. 2. 



PYREXOMYCE'TES. That portion of 

 the Ascomycetous and Coniomycetous Fungi 

 having a closed, nuclear fruit ; standing 

 opposed to the Discomycetes, with open 

 fruits, like the Angiocarpous and Gymno- 

 carpous Lichens. Now sunk in Sphseriacei. 



PYRENOP'SIS, Nyl. A genus of Col- 

 lemaceous Lichens. 8 species; on rocks. 

 (Leighton, Lich. Flora, 14.) 



PYRENO'THEA, Fries. A genus of 

 Limborieae (Angiocarpous Lichens), con- 

 taining a number of species separated from 

 Veriucaria, on account of the spores being 

 free in the perithecia and not developed in 

 thecae. The bodies taken for spores, how- 

 ever, are spermatia contained in spermo- 

 gonia, the sporiferous perithecia being 

 apparently unknown (see LICHENS). 



BIBL. Leighton, Ang. Lichens, 65; Tu- 

 lasne, Ann. Sc. N. 3. xviii. 217. 



PYRSONE'MA, Leidy. A genus of 

 Holotrichous Infusoria. Body fusiform, 

 with a cord-like longitudinal undulating 

 "border. P. vertens, in the intestine of the 

 white aut(Termes); length 1-200". (Kent, 

 Inf. 554.) 



PYRULI'NA, D'Orb. A neat acuto- 

 pyriform Polymorphina. Fossil in the 

 Chalk, and German Tertiaries. 



BIBL. D'Orbiguy, Mem. Soc. Geol. Fr. 

 iv. 43 ; Bradv, Parker and Jones, Linn. Tr. 

 xxvii. 219. 



PYTHIUM, Pringsheim. A supposed 

 genus of parasitic Unicellular Algae, the 

 true nature of which, however, is yet 

 doubtful. 



P. entophytum (PI. 5. fig. 8) occurs in 

 this country in diseased cells of Confervoid 

 Algae. It consists of minute flask-shaped 

 bodies, taking the place of the proper cell- 

 contents, finally pushing the neck-like por- 

 tion through the wall of the cells, outside 

 of which it bursts and discharges active (?) 

 molecules, which Pringsheim regards as 

 gonidia. P. monospermum grows upon 

 insects in water, in the manner of Achlya ; 

 and he refers this genus to the family 

 Saprolegnieae. 



BIBL. Pringsheim, Jahrb. wiss. Bot. i. 

 289; Carter, Ann. N. H. 2. xvii. 101; 

 Henfrey, Tr. Mic. Soc. New Series, vii. 25 ; 

 Currey, Mic. Jn. v. 211 ; Rabenht. Alg. iii. 

 276. 



PYXIC'OLA, Kt, A genus of Peritri- 

 chous Infusoria; like Cothurnia, but with 



