MYRIOCEPHALUM. 



[ 448 ] 



MYRIOTRICHIA. 



The structure of the trophi varies in the 

 different genera. The labrum is small, and 

 usually consolidated with the cephalic plate. 

 The mandibles (PI. 28. figs. 25, 26 b) are often 

 large and powerful, somewhat resembling 

 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. 28. fig. 26 c) is often deeply 

 cleft, its anterior and inner margin elegantly 

 toothed, and to it are attached the labial 

 palpi (fig. 26 c). In some the labial palpi 

 and mandibles are absent, the labium form- 

 ing a kind of sheath or suctorial rostrum. 



One or two pairs of legs, with a single 

 claw, are attached to each joint of the body. 



The internal structure resembles that of 

 other 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 M3Tiapoda live in dark places, be- 

 neath the bark of trees, under dead leaves, 

 stones, &c. 



They form very interesting objects when 

 properly prepared and mounted. 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 should be slit up with fine scis- 

 sors, and the viscera removed ; the integu- 

 ment being gently compressed, and dried as 

 above. 



BiBL. Newport, Linn. Trans, xix. ; id. 

 Phil. Trans. 1841 ; Gervais, Ann. des Sc. 

 nat. 2 ser. vii. ; Leach, Linn. Trans, xi. ; 

 R. Jones, Todd's Cycl. Anat. and Phys. iii. 



MYRIOCEPHALUM, De Not. See 

 Cheirospora. 



MYRIONEMA, Grev.— A genus of Myri- 

 onemacese (Fucoid Algae), consisting of mi- 

 nute 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 oosporanges producing zoospores ; 

 and it is probable that they are accompanied 

 by trichosporanges, as in Elachistea. 



1 . M. strangulans, Grev. Patches convex. 



confluent ; erect filaments clavate ; ' spores' 

 on the decumbent filaments. Forming dark 

 brown dot-like spots on UIvcb, or little rings 

 round EnteromorjjhcB. Grev. Sc. Crypt. Flor. 

 pi. 300. 



2. M. Leclancherii, Chauv. Patches or- 

 bicular; erect filaments cylindrical; 'spores' 

 on the decumbent filaments. Forming 

 patches 1 -12 to 1-4" in diameter (at first like 

 a ColeochcBte) on decaying fronds of Rhody- 

 menia and Ulva. Harv. Phyc. Brit, pi, 41 A. 



3. M. punctiforme, Lyngb. Patches glo- 

 bose; filaments tapering to the base; 'spores' 

 fixed to the erect filaments near their bases; 

 'spores' very narrow. Forming minute 

 patches on Ceramia, Chylocladia. Harv. 

 I. c. pi. 41 B. 



4. M. clavatum, Carm. An obscure spe- 

 cies. Hook. Brit. Fl. ii. pt. 1. p. 39*1. 



BiBL. Op. cit. sup. ; Harvey, Brit. Mar. 

 Alg.\). 51.pl. 10 E. 



MYRIONEMACE.^.— A family of Fu- 

 coidese. Olive-coloured sea- weeds, with a 

 tuber-shaped or crustaceous spreading frond, 

 sometimes minute and parasitical. Ovoid 

 oosporanges and filamentous trichosporanges 

 attached to the superficial filaments, and 

 concealed among them. 



Synopsis of the British Genera. 



I. Leathesia. Frond tuber-shaped. 



II. Ralfsia. Frond crustaceous. 



III. Elachistea. Frond parasitical, 

 consisting of a tubercular base bearing pen- 

 cilled erect filaments. 



IV. Myrionema. Frond parasitical, 

 forming a flat base bearing cushion-like tufts 

 of decumbent filaments. 



MYRIOTRICHIA, Harv.— A genus of 

 Ectocarpaceae (Fucoid Algae), consisting of 

 minute epiphytic plants, forming tufts of 

 capillary filaments on larger Algae. The 

 filaments are simple jointed tubes, set all 

 over with minute, simple, spore-like ramules, 

 which again are clothed with very slender, 

 long, articulated filaments. The fructifica- 

 tion consists of oval oosporanges on the side 

 of the main axis, producing zoospores ; pro- 

 bably also trichosporanges exist. 



1. M. claviformis, Hook. Main filament 

 with quadrifarious ramules, increasing in 

 length upwards. Fronds 1-2" long, forming 

 tufts on Chorda lomentaria. Harv. Phyc. 

 Brit. pi. 101. 



2. M. jiliformis, Harv. Main filaments 

 very long, often flexuous, set at irregular 

 intervals with oblong clusters of minute pa- 

 pilliform ramules. Frond 1" or more long. 



I 



