A REG A. 



[ 72 ] 



ARRE1SIURUS. 



nutans, Sowerby ,t. 260 ; Arcyriaflava, Grev. 

 Sc. Crypt. FL t. 309. 



A. umbrina, Schum. Spores and capilli- 

 tium ochraceous, capillitiuin erect; peri- 

 dium ovate. 



A. ochroleuca, Fr. Spores and capilli- 

 tium pale-ochraceous, peridium globose, 

 evanescent; smaller than the preceding; 

 1-12" high. 



B[BL. Berk. Hooker's Brit. Fl. ii. pt. 2. 

 p. 318; Crypt. Sot. p. 337; Fries, Summa 

 Veget. p. 456; Rost. Sluzowce ; Cooke, 

 Myx. 



ARE'CA,L. A genus of flowering plants 

 (Fam. Palmaceae). The albumen of the seed 

 of the Areca catechu (the Areca nut, as it is 

 called) affords a good instance of horny con- 

 sistence produced by secondary layers upon 

 the cell-walls (PL 38. tigs. 21 & 22). See 

 ALBUMEN (of seeds). 



AREG'MA, Fries. A genus of Conio- 

 mycetous Fungi closely allied to Puccinia, 

 comprising the species with many cells 

 which occur on various Rosaceae, as the 

 common dark parasite of the Rose and 

 Bramble. Like Puccinia, the species always 

 seem connected with a Uredinous form, and 

 are propagated by secondary spores pro- 

 duced on the multiseptate bodies after ger- 

 minating. 



BIBL. Fries, Summa Veg. p. 507 ; Berk. 

 Crypt. Bot. p. 325 ; Tulasne, Ann. d. Sc. Nat. 

 1847, Jan. p. 12; De Bary, Ueb. d. Brand- 

 pilze. 



ARE'OLAR TISSUE of animals. See 

 CONNECTIVE TISSUE. 



AR'GAS,Walck. A genus of Arachnida, 

 of the order Acarina and family Ixodea. 



Char. Rostrum inferior, concealed, as also 

 the palpi, beneath a projection of the ante- 

 rior part of the body ; under part of body 

 granular, not scaly, and consisting of a single 

 piece ; first joint of the palpi longest ; legs 

 approximate at their insertion, feet termi- 

 nated by two claws, but no vesicle. 



These animals are frequently parasitic 

 upon pigeons, fowls, &c. ; some live in 

 gardens. 



A .reflexus( Tthynchoprion Cb/wm&^,Herm. ) . 

 Body marked with tortuous furrows and de- 

 pressions, yellowish or violet after food. On 

 pigeons, especially when young. 



A. persicus. Blood-red colour, back co- 

 vered with scattered elevated white spots. 

 The venomous bug of Persia ; said to cause 

 death in the human subject. 



There are other species. 



BIBL. Gervais, Walcken. Apteres, iii. ; 



Murray, EC. Entom. 180 (figs of all species) ; 

 Megnin, Paras. 1880, 133. 



AR'GULUS, Mull. A genus of Crusta- 

 cea, of the order Siphonostoma and family 

 Argulidae. 



Char. Carapace membranous, covering 

 the cephalothorax like a shield ; antennae 

 four, short, concealed beneath the carapace, 

 anterior two-jointed, terminal joint hooked ; 

 posterior four-jointed; rostrum acuminate ; 

 five pairs of legs, the place of the first (6th) 

 pair being occupied by two suckers ; second 

 pair short, five jointed, the two basal joints 

 spinous, the last joint with two small hooks ; 

 the last four pairs of legs two-cleft, and 

 furnished with ciliated filiform processes. 



A.foliaceus (PI. 20. fig. 1). Parasitic on 

 the stickleback (G aster ostem) and other 

 fishes ; carapace greenish. 



BIBL. V. d. Hoeven, Zool. ; Baird, Brit. 

 Entom. p. 242 ; Thorell, Ann. N. H. 1866, 

 xviii. p. 149. 



ARPAC'TICUS, Baird. A genus of 

 Entomostraca, of the order Copepoda and 

 family Cyclopidee. 



Char. Head undistingriishable from tho- 

 rax ; foot-jaws two pairs, forming strong 

 cheliform hands; antennae in male furnished 

 with a swollen hinge-like j oint ; antennules 

 (inferior antennae) simple; legs five pairs, 

 the fifth pair rudimentary; eye single; ovary 

 single. Two species : 



A. chelifer and A. nobilis. Marine, closely 

 resembling Cyclops. 



BIBL. Baird, Brit. Entom. p. 212. 



ARRENU'RUS, Duges. A genus of 

 Arachnida, of the order Acarina and family 

 Hydrachnea ( = Caudate Hydrachnae). 



The posterior part of the body of the male 

 is narrowed and produced into a truncate or 

 cylindrical appendage. The body of the fe- 

 male is truncated posteriorly. The prolon- 

 gation is terminated by two angles and a 

 sinuous intervening margin. At the middle 

 of the latter is situated the penis; above 

 which are two hooks. In both sexes the 

 back is hard, crustaceous, as if shagreened, 

 or spinous. In some species the thicker 

 layer of the skin is furnished with a number 

 of conical apertures (PI. 6. fig. 12). The 

 eyes are two, distinct, blackish. The intes- 

 tinal caeca are distinguishable through the 

 skin. The mouth is round and surrounded 

 by a kind of hood (PL 6. fig. 13, c). 



Arrenurus viridis, Duges's typical species 

 (PL 6. fig. 13), has the palpi short and cla- 

 vate (a); the fourth joint longest and largest, 

 the fifth falcate, and the mandibles ungui- 



