014 Transactions of the Society. 



rarely nnsymmctrioal, inserted close to border, circular, or transversely 

 elliptical, hyaline, about 0-005 mm. broad. 



This species, founded on Hardmun's South American valves, is not 

 to be separated from the specimens in the collections of Greville and 

 Hardman labelled E. marginatus. 



Habitat: Bridgewater deposit, Barbadoes (Jobnson!); Cambrido^e 

 deposit, Barbadoes (Johnson ! Greville!); Colon (Hardman ! Kitton!); 

 shell cleaning?', South America (Hardman) ; Gulf of California 

 (Hardman !), 



Species exclus-e vel inquirend^. 



E. amerieanus Ehrb. (fide Kalfs in Pritch. Inf., p. 843). E. 

 ffermanicns Ehrb. (iMon. Ber. Ak., 18-14, p. 81). E. quafernarius 

 Ehrb. (ibid. 1814, p. 81). E. quinarius Ehrb. (ibid. 1844, p. 81). 

 E. monstruosus Ehrb. (ibid. 1884, p. 81), and E. argus W. Sm. (Syn. 

 Brit. Diat.,i. p. 24) are Aulacodiscus argus (Rattray, Journ. Boy. Mic. 

 Soc. Lend., 1888, pp. 373, 374). 



E. Bogersii Ehrb. (Mon. Ber. Ak., 1844, p. 81), and E. BaiJeyi 

 Ehrb. (ibid.) are Aulacodiscus Bogersii Sch. (Hattray ibid.), 



E. crux Kutz. (Sp. Alg., p. 135) is Aidacodiscus crux Ehrb. 

 (Mon. Ber. Ak., 1844, p. 76). 



E. ? tripes Johnson (Amer. Jonrn. Sci., vol. xiii., 1852, p. 33) is 

 said to resemble Coscinodiscus radiatus, but it possesses 3 processes 

 similar to those of Eupodiscus. Specimens so named have been 

 procured from Chincha guano near the Pacific Coast. 



E. crassus W. Sm. (Syn. Brit. Diat., i. p. 24, pi. iv. fig. 41) is 

 identical with Actinocyclus octonarius Ehrb. (Mon. Ber. Ak., 1837, 

 p. 61) Nvhich is one of the forms of A. Ehrenhergii Kalfs (Pritch. Inf., 

 p. 834). 



E.fidvusW. Sm. (Syn. Brit. Diat.,i. p. 24, pi. iv. fig. 40), belongs 

 to Actinocyclus (see p. 897). 



E. scidptus W. Sm. (Syn. Brit. Diat., i. p. 23, pi. iv. fig. 42) is 

 Auliscns sndptus Balfs (see p. 884). 



E. tenellus de Breb. (Mem. Soc. Imp. d. Sci. Nat. Cherb., 1854, 

 p. 257, fig. 9) belongs to Actinocyclus. The pseudonodule near the 

 border is evident, and the structure otherwise is actinocycloid. De 

 Brebisson united the specimen with some doubt to Eupodiscus, and 

 Donkin, though endorsing the same doubt, did not remove it from 

 Eupodiscus (Quart. Journ. 3[ic. Sci., 1861, p. 7). 



E. crucifer Shadb. (Trans. IMic. Soc. Lond., 1854, p. 16, pi. i. 

 fig. 12) and E. Peter sii Kiitz. (Sp. Alg., p. 135) are Aulacodiscus 

 Petersii (Rattray, ibid., 1888, p. 36ij). 



E. Balfdi W. Sm.* (Syn. Brit. Diat., ii. p. 86) is Actinocyclus 

 Baljsii (Halfs in Pritch. Inf., p. 835). E. sparsus Greg. (Trans. Mic. 



• Prof. W. Smith was induced to separate his Eupndiscus Ralfsii, E. fulvus, and 

 E. cras-^us from Actinocyclus as he limited the latter genus to frustules possessing 

 undulate valves. He however recognized the presence of the p.seudonodule which is 

 a structural feature more significant tlian meic form of surface, aiul also a better guide 

 to natural relationship. 



