LAGENELLA. 



[ 878 ] 



LATEX. 



i. 1 ; Clark, ibid. 1849. iii. 382, and 1850, 

 v. 166; D'Orbigny, Foraminif.fossiles. 



LAGENELLA, Ehr A genus of Infu- 

 soria, of the family Cryptomonadina. 



Char. A red eye-spot present ; carapace 

 with a beak or neck like that of a bottle. 



L. euchlora (PL 24. figs. 35 & 36). Ovate, 

 neck short, truncate ; carapace hyaline, con- 

 tents green. Aquatic; length 1-1150". 



Dujardin places this organism in the genus 

 Cryptomonas. 



It probably consists of the spore of an 

 Alga. 



BIBL. Ehrenberg, In/us, p. 45 ; Dujardin, 

 In/us, p. 333. 



LAMINARIA, Lamx. A genus of Lami- 

 nariacese (Fucoid Algae), with large, flat, sti- 

 pitate fronds, several species of which are 

 common on rocky shores, attached to rocks 

 and stones. L. saccharina has a riband- 

 shaped frond, growing from 2 to 12 feet 

 long. L. digitata has a broad frond, 1 to 5 

 feet long, cut into a variable number of seg- 

 ments. The internal structure presents three 

 layers, the outermost forming a kind of epi- 

 dermis. The oosporanges(sTpores of anthers), 

 containing ciliated zoospores which repro- 

 duce the plant, are the only kind of fructifi- 

 cation yet observed. They are little elon- 

 gated sacs, nestling between epidermal cells 

 of peculiar structure, standing perpendicu- 

 larly upon the central substance of the frond. 

 In L. saccharina the presence of the spo- 

 ranges is denoted by a longitudinal brown 

 mark in the centre of the frond ; in L. digi- 

 tata they occur in flat patches on the extre- 

 mities of the digitations. The zoospores are 

 little olive-coloured bodies, with an anterior 

 and posterior cilium. Thuret has seen them 

 germinate. 



BIBL. Harvey, Brit. Mar. Alg. p. 29. pi. 

 4; Phyc. Brit. pi. 192. 223. 241, &c.; Gre- 

 ville, Alg. Brit. t. 5 ; Thuret, Ann. des Sc. 

 nat. 2 ser. xiv. p. 240. pi. 30. fig. 1-4. 



LAMINARIACE^. A family of Fucoi- 

 deae. Olive-coloured inarticulate sea-weeds, 

 whose oosporanges are superficial, either 

 forming indefinite cloud-like patches, or co- 

 vering the whole surface of the frond. 



Synopsis of the British Genera. 



* Frond stalked, the stalk ending in an 

 expanded leaf-like portion. 



I. ALARIA. .Lea/membranaceous, with a 

 cartilaginous percurrent midrib. 



II, LAMINARIA. Leaf (simple or cleft) 

 without any midrib. 



** Frond simple, leafless. 



III. CHORDA. Frond cylindrical, hol- 

 low; the cavity interrupted by transverse 

 partitions. 



LAOMEDEA, Lamx. A genus of Po- 

 lypi, of the order Anthozoa. 



Char. Polypidom rooted, erect, jointed at 

 regular intervals, the joints ringed and in- 

 crassated ; cells alternate, on short pedun- 

 cles, campanulate ; vesicles axillary ; polypes 

 hydriform. 



Agrees very nearly with Campanularia. 



Four British species, found upon marine 

 Algae, stones, &c., between tide-marks. 



BIBL. Johnston, Brit. Zoophytes, p. 101. 



LARVAE. In animals which pass through 

 certain marked stages of development, or 

 undergo metamorphosis, as it is called, the 

 condition in the first of these stages is called 

 the larval state, and the animal itself is 

 called a larva. 



The aquatic larvae of several insects are 

 well-known microscopic favourites, on ac- 

 count of their transparence, which allows 

 the action of the dorsal vessels, with the cir- 

 culation of the nutritive liquid, to be seen, 

 and their curious respiratory organs. A few 

 of the more common aquatic larvae and their 

 parts are represented in PL 28. figs. 1. 

 14-17. 19-22, 29; these are noticed more in 

 detail under their respective heads. 



The aquatic larvae of some reptiles are 

 admirable objects for exhibiting the circula- 

 tion of the blood, the development of tis- 

 sues, &c., as those of the frog (tadpoles) and 

 of the Triton. 



LASIOBOTRYS, Kz. A genus of Peri- 

 sporacei (Ascomycetous Fungi). 



L. LonicercB grows on the living leaves and 

 stems of various kinds of Honeysuckle, 

 forming little heaps seated on a tuft of ra- 

 diating filaments. The so-called peridioles 

 appear to be sclerotioid bodies, the superfi- 

 cial cells of which are converted into true 

 perithecia, becoming free on the surface; 

 these contain numerous asci when mature, 

 but the spores have not been observed. 



BIBL. Berkeley, Brit. Flora, ii. pt. 2. 

 p. 324, Ann. Nat. Hist. 2 ser. ix. p. 386. 

 pi. 12. fig. 44; Fries, Summa Veg. p. 406; 

 Greville, Sc. Crypt. Fl. pi. 191. 



LASTR^A. A genus of Polypodaous 

 Ferns. See NEPHRODIUM. 



LATEX. The name applied to the pecu- 

 liar juices, becoming milky when exposed to 

 air, contained in the * milk-vessels/ or lati- 

 ciferous canals of plants, especially abundant 

 in Euphorbiaceae, Papaveraceae, Cichoraceae, 



