AMPHIMONAS. 



AMPHIPRORA. 



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

 b, side view). 



6. A. meleagris (Loxophyttum meleagris, 

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

 b, anterior portion in side view). 



7. A. longicollis, E. Colourless ; 1-120 to 

 1-96". 



8. A. papillosus, E. Yellowish-brown; 

 1-600 to 1-430". 



9. A. 'borax, D. (Trachelius vorax, E.). 

 Colourless* 



10. A. ovum, D. (Trachelius ovum, E.). 

 Colourless. 



BIBL. Ehr. Infusionsth., p. 354; Dujardin, 

 In/us., 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 narrowing 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" (PL 23. fig. 1 1). 



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 Diatomacese. 



Char. Unattached ; frustules solitary, bi- 

 valve, pentagonal and siliceous. Species : 



1. A. pentacrinus ', diam. 1-240 . 



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



Both are fossil. Ehrenberg questions 

 whether the latter does not consist of calca- 

 reous particles of an Echinoderm ! 



BIBL. Ehrenb. Eericht.d. Eerl. Ak. 1840 

 and 1843, Abhl 1841; Kutzm&Bacill. p. 136. 



AMPHIPLEURA, Kiitz. A genus of 

 Diatomaceae. 



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 (PL 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. 



The valves appear to resemble those c 

 Nitzschia in their inequality ; but they ar 

 compressed in the opposite direction to thos 

 of that genus, and thus the median lines c 

 both valves are visible at once. That th 

 lines seen upon the frustules are the same a 

 the median lines of the separated valves, i 

 evident from their exhibiting the termim 

 expansions. This view is confirmed by th 

 sides of the frustules being half as broad agai: 

 as the separate valves. British species : 



1. A.pellucida (Navicula acus of Mr. Sol 

 litt and the Hull naturalists, but not th 

 Nov. acus of Ehrenberg, which is the Synedr 

 subtilis of Kiitzing) (PL 12. fig. 7, a,b). Aqua 

 tic, valves linear-laneeolate ; length '0044' 

 The valves are furnished with longitudina 

 and transverse striae (rows of depressions ? 

 of extreme delicacy, requiring the very bes 

 object-glasses of the largest aperture, and th 

 most oblique light to render them visible 

 Mr. Sollitt estimates them at 125 to 130 i: 

 1 - 1 000". These valves form the most difficul 

 test-objects at present known, for angula 

 aperture and obliquity of light; but those o 

 some species of other genera are probabl 

 much more difficult. 



2. A. rigida. Marine ; valves narrow! 

 linear-lanceolate, slightly sigmoid; lengtl 

 0067" (PL 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,slightl; 

 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 

 tomaceae. 



Char. Frustules free, solitary, constricte< 

 in the middle ; valves convex, having a me 

 dian keel, with a nodule at each end, am 

 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 Ion 

 gitudinal plane almost at right angles to tha 

 of the other. The surface of the valves i: 

 more or less distinctly marked with trans 

 verse striae, which under high powers am 

 proper manipulation are resolvable into dot 

 or minute depressions, arranged as in PL 1 1 

 fig.8. SeeDiATOMACE^;. British species : 



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

 a, side view; b, front view). 



2. A. constricta, E. 



3. A. didyma, Sm. 



