872 



SYSTEMATIC HISTORY OF THE INEUSORIA. 



Cfimhriata (Fi.^. — Valve oval, witli 

 a crenate intramarginal line ; coarse 

 transverse puncta reaching the median 

 line. EB. 1858 ; Bri JMS. vii. p. 179, 

 pl. 9, f. 43. Corsican Algae. This species 

 18 readily distinguished by its peculiar 

 looped margin. 



Doubtful and undescrihed Species. 



C. Navicula (E). — Striated ; the navi- 

 cular side ovate ; the front view narrow- 

 linear, with an obscure median, lon^- 

 tudinal fui-row. KSA. p. 63. Baltic, 

 parasitic on Bacillaria paradoxa. 1-864". 



C. paradoxa, EM. pl. 9. 2. f. 5. Fossil. 

 Puy de Dome. Figures small, elliptic, 

 smooth, with one or two median longi- 

 tudinal lines and no nodule. 



C. Britannica (Nag.). — Large, elliptic, 

 smooth, with an accessory limb, mar- 

 ginal outwardly curved lines, and a di- 



stinct median nodule. KSA. p. 890. On 

 British Algae. 



C. tefiuissima (Nag.). — Elliptic, very 

 thin, with concave venter and con- 

 vex dorsum, sometimes with a narrow, 

 opaque, crenulated limb. KSA. p. 890. 

 On British marine Algae. Varies in 

 breadth and in presence or absence of 

 striae and accessory border. 



C. disciformis (E.), C navicularis (E), 

 C. Scutum (E.), Swan River ; C. stellata 

 (E.), C. undata (E.), Western Asia; C. 

 tumida (E.), River Jordan ; C. acuta (E.), 

 Ural Mountains ; C. turgida (E.), Siberia ; 

 C. Indica (E.), C. Bramapiitra (E.), C. 

 angusta (E.), India; C. Sol (E.), Oasis 

 of Jupiter Ammon, Africa ; C. Stella (E), 

 Teneriffe ; C. Glans (E.), C. Brasilieiisis 

 (E.), C. lirata (E.), Brazil; C. Morrisii 

 (S.), Black Sea. 



FAMILY XV.— ACHNANTHE^. 



Frustnles genuflexed downwards, either free, adnate, or stipitate, each 

 lateral surface having a median longitudinal line and the inferior one a 

 central nodule or stauros also. The Achnantheae, like the Cocconeideae, have 

 a nodule only on the inferior valve; but this is almost the only point of 

 resemblance. The bent frustule and dissimilar lateral surfaces distinguish 

 this family from every other. In their mode of growth the Achnantheas 

 resemble the Biddulphieae. 



Genus ACIINANTHIDIUM(Kutz.). — Frustnles unattached, solitary or 

 few together, rarely numerous, in front view linear, bent ; ventral valve with 

 median line and central and terminal nodules ; dorsal valve without a central 

 nodule. The Achnanthidia resemble unattached frustnles of Achnanthes, but 

 are generally very minute, and their proper position is stiU somewhat doubtful. 

 '' Admitting it to be proved that in the species of this genus there positively 

 exists a median nodule in one of the lateral surfaces and not in the other, 

 and that two puncta exist in the extremities of the primary surfaces, as 

 stated in the definition of the order and in that of the family, — admitting this, 

 we should still have to decide whether the uncertain relations of these cha- 

 racters to other families, and their inconstancy, will give us any right to 

 erect a distinct genus on principles so slight and precarious " (Meneghirii). 



rounded ; striae obscure. = Navicula tri- 



* Frustules minute, smooth or obscurely 

 striated. 



AcHNANTHiDiuM microceplialum (K.). 



— Frustules extremely minute ; valves 

 lanceolate, with capitate apices ; striae 

 obsolete. KB. p. 75, pl. 3. £ 13 & 19 ; 

 SBD. ii. p. 31, pl. 61. f. 380. Fresh 

 water. Em-ope. (xiv. 15.) Front view 

 narrow-linear. 1-1680". 



A. trinode (Ar.). — Frustules genicu- 

 late; valves with one central and two 

 terminal inflations ; median line and 

 central nodule distinct ; extremities 



nodis, SBD, ii. p. 94. Fresh water. 

 Britain, {yiu. 9.) 



A. lanceolatum (Breb,). — Frustules 

 minute ; valves oblong-lanceolate, with 

 obtuse ends and turgid centre ; striae 

 obscure. Breb. in KSA. p. 54 ; SBD. ii. 

 p. 30, pl. 37. f. 304. Fresh water. Eu- 

 rope. Frustules 2 to 100; striae 40 in 

 •001", S. The transverse band of the 

 lower valve sometimes extends to both 

 margins, sometimes is bifid, and on one 

 half only. 



K, delicatidum (K.). —Frustules mi- 



