AMPHIMONAS. 



[ so J 



AMPHIPRORA. 



1-720 to 1-144" (PI. 23. f. 10 «, from above; 

 b, side view). 



6. A. meleagris {LoxophyUum meleogris, 

 D.). Colom-less; 1-72" (PI. 24. f. 42 a; 

 b, anterior portion in side view). 



7. A.longicolUs,^. Colourless; 1-120 to 

 1-96". 



8. A. jjajnllosus, E. Yellowish-bro^AH ; 

 1-600 to 1-430". 



9. A. vorax, D. {Traclielius vorax, E.). 

 Colourless. 



10. A. ovum, D. {Traclielius ovum, E.). 

 Colourless. 



BiBL. Ehr. Infusionstli., p. 354; Dujardin, 

 Infiis., p. 483. 



AMPHIMONAS.— A genus of Infusoria, 

 of the family Monadina (Duj.). 



Char. Of irregular and variable form, 

 having at least two filaments, one anterior 

 the other lateral, arising from a narro\ving of 

 the body, or both lateral, with or without a 

 tail-like prolongation. 



Found in kept saline solutions and marsh 

 water. Species : — 



1. A. dispar. Colourless; length 1-3860 

 to 1-2700" (PI. 23. fig. 11). 



2. A. caudata {Bodo saltans ?, Ehr.). 

 Colourless; 1-2180 to 1-1270". 



3. A. brachiata. Colourless. 



BiBL. Dujardin, Infus., p. 292. 



AMPHIPENTAS, Ehr.— A doubtful or- 

 ganism, regarded by Ehrenberg as a genus 

 of Diatomaceae. 



Char. Unattached ; frustules solitar}^ bi- 

 valve, pentagonal and siliceous. Species : — 



1. A. pentacrinus; diam. 1-240". 



2. A. alternans (PI. 19. fig. 11). 



Both are fossil, Ehrenberg questions 

 whether the latter does not consist of calca- 

 reous particles of an Echinoderm ! 



BiBL. Ehrenb. Bericht.d. Berl. Ak. 1840 

 and 1843,^6^/. 1841; Kiitzing,Baa7/. p. 136. 



AMPHIPLEURA, Kiitz.— A genus of 

 Diatomacese. 



Char. Frustules free, straight or slightly 

 sigmoid ; valves lanceolate or linear-lanceo- 

 late, each with two lateral longitudinal lines. 



Ehrenberg regards the lines as corre- 

 sponding to ridges. We have only had 

 an opportunity of examining the frustules of 

 one species, A.pellucida (PI. 12. fig. 7 a, side 

 view of frustule ; b, of valve). In this, the 

 frustules are very much flattened, so that the 

 front view can only be seen as they are 

 rolling over. The valves are furnished with 

 a median line, which is thickened and ex- 

 panded longitudinally at each end. There 

 is no median nodule. 



1 



The valves appear to resemble those of 

 Nitzschia in their inequality ; but they are 

 compressed in the opposite direction to those 

 of that genus, and thus the median lines of 

 both valves are visible at once. That the 

 lines seen upon the frustules are the same as 

 the median lines of the separated valves, is 

 evident from their exhibiting the terminal 

 expansions. This view is confirmed by the 

 sides of the frustules being half as broad again 

 as the separate valves. British species : — 



1. A.pellucida {Navicula acus of Mr. Sol- 

 litt and the Hull naturalists, but not the 

 Nav. acus of Ehrenberg, which is the Synedra 

 subtilis oi^sMtzmg) (PI. 12. fig. 7, a, 6). Aqua- 

 tic, valves linear-laneeolate ; length '0044". 

 The valves are furnished with longitudinal 

 and transverse strise (rows of depressions ?) 

 of extreme delicacy, requiring the very best 

 object-glasses of the largest aperture, and the 

 most oblique light to render them visible. 

 Mr. Sollitt estimates them at 125 to 130 in 

 1-1000". These valves form the most difficult 

 test-objects at present known, for angular 

 apeitm-e and obliquity of light; but those of 

 some species of other genera are probably 

 much more difficult. 



2. A. rigida. Marine ; valves narrowly 

 linear -lanceolate, slightlv sigmoid; length 

 •0067" (PI. 12. fig. 7^c, side view). 



3. A. Danica. Valves lanceolate, truncate; 

 length '0025"; found on the shores of Den- 

 mark. 



4. A.inflexa. Marine; linear,lunate,slightly 

 attenuate at ends, obtuse ; length •0030'. 



BiBL. Kiitzing, Bacillar., p. 103; Spec. 

 Alg. p. 88 ; Smith, Brit. Diat. i. p. 45. 



AMPHIPRORA, Ehr.— A genus of Dia- 

 tomacese. 



Char. Frustules free, solitar}^, constricted 

 in the middle ; valves convex, having a me- 

 dian keel, with a nodule at each end, and 

 either a nodule or stauros in the middle. 



Marine, or inhabitants of brackish water. 



The frustules are sometimes much twisted, 

 occasionally resembling a violin in form, 

 from one-half of the frustule being on a lon- 

 gitudinal plane almost at right angles to that 

 of the other. The surface of the valves is 

 more or less distinctly marked with trans- 

 verse strise, which under high powers and 

 proper manipulation are resolvable into dots 

 or minute depressions, arranged as in PL 11. 

 fig.8. SeeDiATOMACE^. British species: — 



1. A. alata, E. Common (PI. 12. fig. 8. 

 a, side view ; b, front view). 



2. A. constricta, E. 



3. A. didyma, Sm. 



