BRITISH DIATOMACE^E. 49 



toma auritum, and which is probably identical with the present, when he 

 says, " the auricular angles give to the frustules the appearance of micro- 

 scopic wool -packs." 



Plate XLIV. 321, Plate XLV. 321, and Plate XL VI. 321. 



2. Biddulphia aurita, Breb. Valve elliptical-lanceolate, with a 

 central inflation armed at its summit with two or three awl-shaped 

 spines ; cellular structure obscure ; processes horn-like, obtuse, in- 

 flated at base. Length of valve "0005" to -0022". v.v. 



De Brebisson, Consid. sur les Diatomees, 1838, p. 12. Ralfs, Ann. vol. 12. 

 viii. 4. Diatoma auritum, Lvng. Tent. lxii. D. Odontella aurita, Ag. 

 Consp. p. 56. Eng. Bot. tab. 2842. Kiitz. Bacill. xxix. 88. Benti- 

 cella aurita, Ehr. Microg. xxxv, A. xxxiii. 7. 



Marine. Eastbourne, Sussex, Feb. 1842, Mr. Jenner. Poole Bay, June 

 1849; Pevensey, Sussex, Sept. 1850, Nov. 1851, March and May 1852; 

 Cork Harbour, July 1855, W. Sm. River Nene, Norfolk, May 1853, Mr. 

 S.&nith. The Clyde, Feb. 1854, Mr. Hennedy. Saltcoats, Feb. 1854, Br. 

 Arnott. Milford Haven, March 1 854, Mr. Roper, and May 1 854, Mr. Okeden. 

 Kinghorn, Fife, April 1854, Br. Greville. Newbie Deposit, Prof. Harkness. 



A widely-distributed species, but rarely occurring in much abundance. I 

 quite agree with M. De Brebisson in associating it with the last species, and 

 in cancelling the newer genus Odontella. The existence of septa in B. pul- 

 chella is by no means to be admitted, though the costse may occasionally 

 project to some extent into the interior of the cell ; but the presence of such 

 costae is no more to be regarded as a generic character than that of similar 

 costse in Isthmia nervosa ; yet to separate the latter generically on such 

 grounds from Isthmia enervis, would obviously violate their natural affinities. 

 I ought perhaps to have added to the above synonyms Odontella subcequa, 

 O. obtusa, and O. turgida of Kiitzing and Pritchard, as I am disposed to 

 believe that these species are merely forms of the present, and my Sussex 

 gatherings exhibit variations in outline which closely approximate the forms 

 there occurring to Kiitzing' s figures : in the absence of authentic specimens, I 

 have, however, thought it better to leave the matter open for future deter- 

 mination. 



Plate XLV. 319. 



3. Biddulphia Rhombus, W. Sm. Valve orbicular-lanceolate; spines 

 submarginal, awl-shaped, abbreviated ; cellular structure distinct ; 

 cellules in quincunx; processes horn-shaped. Length of valve 

 •0021" to -0055". v.s. 



Zygoceros Rhombus, Ehr. in Kiitz. Bacill. xviii. 9. Roper, Mic. Trans, vol. 2. 

 vi. 5. 



VOL. II. E 



