MYRIAPODA. 



[ 528 ] 



MYRIONEMA. 



MYRIAP'ODA.— A class of Ai-thropoda. 



Char. Wiugs none ; one pair of antennae ; 

 legs numerous ; thorax not separated from 

 the abdomen. 



These animals are commonly known as 

 centipedes, millipedes, or hundred-legs. 



Body usually long, cylindrical or flattened, 

 and consisting of numerous rings, joints, or 

 somites. Head distinct, and the jointed 

 legs, with a single claw, arranged on each 

 side of the body throughout its length. A 

 few of them are broad, short, and flattened, 



Fig. 504. 



lulus terrestris. Magnified 4 diameters. 



somewhat resembling wood-lice. Behind 

 the antennse are laterally placed the eyes, 

 which in some are absent; they usually 

 consist of a group of ocelli. 



The structure of the trophi varies in the 

 different genera. The labruui is small, and 

 usually consolidated with the cephalic plate. 

 The mandibles (PI. 35. figs. 25, 26 6) are 

 often large and powerful, somewhat resem- 

 bling those of the spiders, and, like them, 

 traversed by a canal, through which the 

 duct of a poison-gland passes. The maxillae 

 are smaller, softer, and furnished with two 

 palpi. The labium (PI. So. fig. 20 a) is 

 often deeply cleft, its anterior and inner 

 margin elegantly toothed ; and to it are 

 attached tiie labial palpi (tig. 26 c). In 

 some the labial palpi and mandibles are 

 absent, the labium forming a kind of sheath 

 or suctorial rostrum. 



The internal structm-e resembles that of 

 the larvae of insects. 



The sexes are separate. The embryo, on 

 escaping from the ovum, has but few legs, 

 sometimes three pairs, at others none, the 

 number being augmented each time the 

 skin is cast ; the same applies to the ocelli. 



The Myriapoda live in dark places, be- 

 neath the bark of trees, under dead leaves, 

 stones, &c. 



They form verj' interesting objects when 

 properly prepared and moimted. The small 

 ones, when slightly compressed between 

 two glasses, dried in that position, subse- 

 quently macerated in oil of turpentine, and 

 mounted in balsam, become very transpa- 

 rent, and show the structure beautifully ; 

 the nervous ganglia and cords are often very 

 distinctly seen in these specimens without 

 dissection. The abdomen of the longer 



specimens shoidd be slit up with fine scis- 

 sors, and the viscera removed — the iuteo-u- 

 ment being gently compressed, and driecf as 

 above. 



BiBL. Newport, Linn. Tr. xix. ; id. Phil. 

 Tr. 1841 ; Gervais, Ann. d. Sc. Nat. 2 ser. 

 vii. ; Leach, Linn. Tr. xi. ; Jones, Todd's 

 Ci/cl. An. iii. ; Fabre, Ann. d. Sc. Nat. 

 1855, iii. ; Packard, Amer. Natural, iv. ; 

 Cope, Tr. Amer. Ent. Soc. 1870 ; Lubbock, 

 Linn. Tr. 1867; Nicholson, Zool. 310 ; Pas- 

 coe, Zool. 90 ; Latzel, Mi/r. 1880. 



MYRIONE'MA, Grev.— A genus of My- 

 rionemacete (Fucoid Algse), consisting of 

 minute epiphytic plants, forming patches of 

 short, erect, simple, jointed filaments, spring- 

 ing from a thin expanded layer of decum- 

 bent cohering filaments. They are described 

 as bearing oblong " spores ; " but these are 

 probably sporanyes producing zoospores, and 

 it is probable that they are accompanied by 

 septate sporanges, as in Elachistea. 



M. strangulans. Patches convex, con- 

 fluent ; erect filaments clavate ; spores ou 

 the decumbent filaments; forms brown dots 

 upon Ulva, or little rings round Entero- 

 morphae. 



M. Ledancherii. Circular; erect fila- 

 ments cylindrical, spores ou the decumbent 

 filaments ; in patches 1-12 to 1-4" in dia- 

 meter ; on decaying fronds of Bhodymenia 

 and Ulva. 



M. punctiforme. Patches globose; fila- 

 ments tapering to the base ; spores very 

 narrow, fixed near the bases of the erect 

 filaments ; on Ceramia and Chi/locladia. 



M. clavatum; obscure. 



BiBL. Harvey, Mar. Akj. 51 ; Grev. Sc. 

 Crypt. Fl. pi. 300; Harv. Phyc. Br. pi. 41 A ; 

 Hook. ^r.i^/. ii. pt. 1. 391." 



