40 • BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Comparison may be made with T. lineolatum Greville (Micro. Journ., 

 1863, pi. 10, fig. 16) fossil at Barbados; also with the questionable 

 variety of T. areolatum Greville figured in Walker and Chase, New 

 Diatoms, plate 3, figure 13, practically identical with what Grunow 

 calls T. jensenianum (Schmidt, Atlas, pi. 77, figs. 15-16). The typi- 

 cal T. areolatum Greville can be found in the Microscopical Journal 

 for 1861, plate 8, figure 13. 



Type.— Cat. No. 43593, U.S.N.M. 



BIDDULPHIA GEMINA (A. Schmidt) Mann 



(Schmidt, Atlas, pi. 80, fig. 16.) 



The original specimen was from the Samoan Islands. 



BIDDULPHIA GIBBOSA (Bailey) Van Heurck 



(Wilkes Exp., p. 181. pL 9, fig. 32; Schmidt, Atlas, pi. 80, figs. 13-21.) 



This diatom's place among the BiddulpTiiae is most questionable. 

 Bailey himself indicated doubt of the correctness of the assignment. 

 The peculiar finishing of its angles, which have, instead of horns or 

 processes, flat disciform areas, bounded on the outer side by semicir- 

 cular ridges, like the eyebrows over an eye, and each accompanied by 

 a single, sharp, curved spine, gives it a strikingly individual aspect. 

 Its delicate texture and beading are also unique. The side view is 

 even more unlike Biddulphia than that of the face. Van Heurck, 

 De Toni, and others suggest its classification under Bailey's genus 

 Lampriscus, in company with such forms as Triceratium circulare 

 Shadbolt, T. sJiadboltianum Greville, T. globosum Bailey, etc. To 

 this group should probably be added that doubtful example of 

 Aulacodiscus, A. Icittonii Arnott. De Toni does not assign to Lam- 

 priscus the single figure of that diatom given in Schmidt's Atlas 

 (pi. 80, fig. 11 ), but for some undivulged reason puts all the others 

 under Aulacodiscus Icittonii. Although favorable to a change of genus 

 I here follow the Biddulphia classification, pending further discussion 

 of the subject. 



BIDDULPHIA GRUNDLERI A Schmidt 



(Schmidt, Atlas, pi. 118, figs. 22-24.) 



BIDDULPHIA GRUNOWIANA (Castracane) Mann 



(Castracane, Chall. Exp., p. 110, pi. 16, fig. 5.) 



BIDDULPHIA HETEROCEROS Grunow 



(Van Heurck, Synopsis, pi. 102, fig. 5.) 



BIDDULPHIA IMPRESSA (Grunow) Mann 



(Van Heurck, Synopsis, pi. 115, figs. 3-6.) 



De Toni (Syl. Alg., p. 986) places this in Lithodesmium , but 

 expresses doubt of its correctness. 



