874 



SYSTEMATIC HISTOET OF THE IN^FUSOEIA. 



than A. hrcvipes, with less turgid dorsum 

 and finer stria3 ; but we doubt whether 

 the}' are truly distinct. 



A. 7'homboides (E.). — Frustules large, 

 striated, very tiu'gid, nearly straight; 

 valves broadly lanceolate, almost rhom- 

 boid, with acute apices; stipes short, 

 thick. EA. p. 121. = A. ventncosa, KB. 

 p. 76, pi. 20. f. 7. Marine. America, 

 Europe. 



A. multiarticulata (Ag.). — Frustules 

 striated, turgid, with rather obtuse 

 angles -, valves elliptic-lanceolate ; stipes 

 stout, short. Ag CD. p. 59 ; KB. p. 76, 

 pi. 20. f. 8. Marine. Em-ope. 1-312". 



A. Capensis (K.). — Frustules striated, 

 turgid, obtuse-angled ; valves lanceolate- 

 elliptic or oblono- ; stipes elongated, stout. 

 KB. p. 76, t. 21. £ 1. Marine. Cape 

 of Good Hope. 1-600". It varies with 

 few or many frustules. 



A. ba cilia r is (E.). — Frustules narrow, 

 striated, each slightly inflexed at the 

 middle, both dorsally and ventrally 

 equally bacillar, with rounded ends ; 

 stipes short. ERBA. 1843, p. 256. Ma- 

 rine. Venice. Often in long series. It 

 is smaller than A. longipes, and more 

 slender than A. brevijjes, E. 



A. subsessilis (K.). — Scattered, of few 

 frustides ; valves linear-oblong, with 

 romided ends; striae monilifonn, 24 in 

 •001"; stipes nearly obsolete. KB. p. 76, 

 t. 20. f. 4; SBD. ii. p. 28, pi. 37. f. 302.= 

 Aclinanthes turgens, EA. p. 121. Common 

 on filiform species of Enteromorpha in 

 salt marshes. Europe, America. 1-1150" 

 to 1-430". (vii. 43.) Easily recognized 

 by its all but sessile frustules. 



A. angustata (Grev.). — Front view 

 nan-ow; length 0060" ; breadth -0004" ; 

 strict 24 in -001". ^ Grev MJ. vii. p. 163, 

 pi. 8. f. 9. In Californian guano. " The 

 striiB agree in number with those of 

 A. subsessilis; the relative length and 

 breadth, however, of the valve, as seen 

 in the front view, is so widely different 

 from the proportions of the species above 

 mentioned, that the possibility of its 

 being a varietv cannot be entertained" 

 (GrevHle). 



A. cristata (Rab.). — Valves oblong- 

 elliptic; striae gently cmwed, coarsely 

 monilifonn, distant, 9 to 10 in -001". 

 Rab D. p. 26, pi. 8. f. 7. Italy. 



K. genujiexa (K.). — Frustules small, 

 striated, turgid, obtuse-angled, strongly 

 bent ; stipes short, rather stout. IvB. 

 p. 76, pi. 21. f. 3. Marine. Genoa. ^ 



A. Gregoriana (Grev.). — Front view 

 of frustule broadly linear; striae very 

 fine ; leng-th -0060" to -0080" ; breadth 



•0010" to -0015". Grev MJ. vii. p. 84, 

 pl._ 6. f. 13, 14. Marine. Scotland. In 

 point of size it rivals A. longipes, but is 

 widely separated from it in the character 

 of the striation alone, to perceive which 

 requires not only a good object-glass but 

 delicate manipulation. As in many of 

 its congeners, the frustules var}^ gTeatly 

 in both length and breadtli (Grev.). 



A. pachypus (Montague). — Frustules 

 sniaU, finely striated, obtuse-angled, 

 rather turgid ; valves elliptic-oblong ; 

 stipes stout, very short. Mont. Flor. 

 Boliv. pi. 1 ; KB. p. 76, pi. 29. f. 83. 

 Marine. Europe, Asia, America. 1-1730" 

 to 1-1320". 



A. parvula (K.). — Frustules minute, 

 nearly straight, obtuse-angled ; valves 

 elliptic-oblong, obtuse, finely striated; 

 stipes rather stout. KB. p. 76, t. 21. f. 5. 

 On Enteromorpha in brackish water. 

 Europe. Frustules stouter than in A. 

 exilis. 



3 * Very mitiute ; strice wanting or 

 indistinct. Fresh water. 



A. exilis (K.). — Frustules slender, 

 linear ; valves lanceolate, tapering to 

 the subacute apices ; striae indistinct ; 

 stipes slender, elongated. KB. p. 76, 

 t. 21. f. 4 ; Rails, ANH. xiii. p. 14. f. 12 ; 

 SBD. ii. p. 29. Fresh water. Europe, 

 Asia, America. (^t:i. 44.) A. exilis is 

 easily knoviii by its minute, slender, 

 hyaline frustules from every other spe- 

 cies except A. minutissima. From that 

 species it differs by its tapering, more 

 lanceolate and acute valves, and by its 

 elongated stipes. 



A. minutissima (K.). — Frustules slen- 

 der, linear; valves linear-oblong, with 

 rounded ends ; striae obsolete ; stipes 

 fine, shorter than the fr'ustule. KB. 

 p. 75, pi. 13. f. 2 c ; Ralfs, ANH. xiii. pi. 14. 

 f. 11. Fresh water. Em-ope. We for- 

 merly considered this a variety of A. 

 exilis, and, still doubting whether the 

 differences are constant, think that Pro- 

 fessor Smith may rightly have united 

 them. 



Doubtfid Species. 



A.? arenicola (Bail.). — Frustides mi- 

 nute, rectangular or slightly curved ; 

 valves lanceolate, striate ; stipes short. 

 Bail. Sm. Cont. ii. p. 38, pi. 2. f. 19. 

 Marine. America. It is possibly a spe- 

 cies of Hvalosira, but requires frirther 

 study (Bail.). 



A. austraJis, EM. pi. 35 a. 2. I 1. 

 South Africa. Frustules linear, uni- 



