FREDERICELLA. 



[ 335 ] 



FRONUICULAKIA. 



which ten are dduhtful. Eahenhorst fid- 

 luits !J spt>cii'8, with nunierous varieties. 



F. capucina, K. (F.rhabdusoma, E., PI. 16. 

 fig. 33). Friistules linear iu front view ; 

 valves narrowly and acutely lanceolate ; 

 breadth of tilament 1-700", Freshwater. 

 Common in pools, &c. 



3. Valves attenuate towards the obtuse 

 ends. 



F. rirescens, Ealfs {F. pectinalis, Ehr.). 

 Frustules in front view linear, rectangular 

 or cuneate ; valves obtuse at tlie contra'ted 

 and produced ends. Freshwater. Endo- 

 chronie green. 



(3. Valves cohering by the angles only. 

 F. striafidn. ^'alves linear, narrowed 

 toward.^ the very obtuse ends. Marine. 



BiBL. Kutzing, BacUl. 45; id. Sp. Ak/. 

 14; Ralfs, Ann. X. H. 1843, xii. 106; 

 Smith, Brit. Diat. ii. 21 ; Rabenhorst, Flor. 

 Alq. i. 118. 



FREDERICEL'LA, Gervais.— A genus 

 of Polyzoa, of the order llippocrepia, and 

 family I'lumatellidas. 



Char. Polypidom fixed, coriaceous, tubu- 

 lar, branched ; polypes protruding from the 

 ends of the branches ; tentacular disk nearly 

 circular ; tentacles about twenty-four, ar- 

 ranged on the margin of the disk in a single 

 series, and invested at their origin by a 

 membrane. Freshwater. 



F. sultana. Polyj^e-cells erect, cylindrical. 

 Height of zoary about 2" ; tufted, shrub- 

 by ; stem dichotomously branched. Eggs 

 bean-shaped, smooth. 



BiBL. AUman, Freshw. Polyzoa {Bai/ 

 Soc), 110; Johnston, Br. Zooph. 40-5. 



FREI'A, CI. & L. — A genus of Infusoria, 

 of the family Bursarina. 



Char. Those of Steyitar, with the buccal 

 spire borne by an anterior membranous bi- 

 lobed expansion. 

 3 species : marine. 

 F. elegans (PI. 62. fig. 1.). 

 BiBL. Clap, and Lachm. Infits. 217; St. 

 Wright, Qu. Mic. Jn. 1862, 217. 

 FREY'A. See Frkia. 

 FROG. — The common frog (Bana tempo- 

 raria) affords a means of studying several 

 interesting points of structure. Thus, by 

 genth' scraping the back of the roof of the 

 mouth with the handle of a scalpel, ciliated 

 epithelium (PI. 49. fig. 13) may be obtained, 

 and the ciliary movement studied. The 

 circulation in the web of the foot, and the 

 phenomena of inflammation may be ob- 

 served, by enclosing a frog in a wet bag, 

 leaving one leg projecting. The bag con- 



taining the frog may then be placed upon a 

 plate of wood, witli a circular aperUue at 

 one end, over which the foot is to be ex- 

 tended by tying the toes with silk or cotton 

 threads to little tacks or nails driven into 

 the wooden plate. Metal " frog-plates " 

 are sold for the purpose. Sections of the 

 kidney of the frog, made with a Valentin's 

 knife, will show the ciliated epitlielium of 

 the necks of the urinary tubules. The 

 circulation of the blood in the lungs and 

 the mesentery may be examined ; but tlie 

 animal should be rendered insensible by 

 chloroform before the experiment. 



The ova of the frog (frogs' spawn) have 

 formed the subject of some of our most 

 interesting experiments on impregnation 

 and development. The larva) (tadpoles) 

 exhibit well the circulation in the gills, 

 tail, and more transparent parts, and afford 

 easily obtained matei-ials for the study of 

 the development of the tissues. The chorda 

 dorsalis is well seen in a young tadpole. 

 The frog and tadpole, however, are inferior 

 in most respects to the Triton and its larvae 

 for exhibiting these phenomena. 



The injected organs of the frog afford 

 most interesting and beautiful preparations, 

 especially the lungs, kidneys, skin, tongue, 

 and Aveb of the foot. The injection should 

 be thrown in at the heart, and the slightest 

 possible force used. The simplest method 

 of killing a frog without injury, is to 

 immerse and retain it in warm water. 



The muscles of the frog often contain 

 a nematoid parasite (^Myonjhtes Weiss- 

 mamii). 



FRONDICULA'RIA, Defr.— This pseu- 

 do-genus comprises flat stichostegian Nodo- 

 sarina, which have geniculate or chevron 

 chambers. They are the extremelj^ com- 

 pressed and dilated forms of the group, 

 having tlie quasi-genus Lhujrdina to connect 

 them with the cylindrical Nodusarke. In 

 Fro7idtctdaria the shell is equilateral ; nar- 

 row-oblong, rhomboidal, or ovate ; greatly 

 compressed; chambers iu a straight row, 

 depressed, each forming two sides of a tri- 

 angle, with the angle sometimes prolonged ; 

 septal lines often raised as ridges ; inter- 

 mediate spaces sometimes striate ; first 

 chamber oval; aperture roimd, on the upper 

 angle. 



Recent in the Atlantic. Fossil in the 

 Tertiaries of Italy, Spain, and West Indies ; 

 and abundant in the Chalk, Gault,Lias, and 

 other fossil clays. Fr. spafhulata (PI. 23. 

 fig. 39) shows the early portion of a speci- 



