OF THE BIDDULPHIE^, 



851 



projections armed with one or two very 

 long filiform spines. BC. 1859. =^eV/- 

 dulphia Baileyii, SBD. ii. p. 50, pi. 62. 

 f. 322,- Ro TMS. vii. p. 12, j)l. 1. f. 5-9. 

 America. In stomach of Ascidise. Hull, 

 Teignmouth. (vi. 11.) Frustules fra- 

 gile, yeUowisli. A well-marked species j 



there is no central pro] ection of the valves, 

 but two slight elevations, furnished with 

 one or more bristles, and di\'iding the 

 margin into three nearly equal portions. 

 The elevations appear situated between 

 the processes, but are really placed on 

 opposite sides. 



Genus HEMIAULUS (Ehr.). — Frustules compressed, subquadrate ; fission 

 perfect, hence not concatenate ; valves without lateral constrictions, each with 

 two processes — that of the one side (apparently ?) open, the other closed. The 

 genus has the habit of Biddulphia, but is devoid of the lateral constrictions. 

 It has the form of a Pandean pipe. As the valves are not constricted, the 

 basal angles are rectangular, and the outer margins of the processes (which 

 are generally attenuated, narrow, and elongated) are straight. 



Hemiaulus antarcticus (E.). — Frus- 

 tules strongly granular ; lateral processes 

 elongated, of one valve truncate, of the 

 other elongated j a short median rounded 

 projection between the processes. EM. 

 pi. 35. A. 22. f. 15. Antarctic Sea. (xi. 54. ) 

 Diam. 1-1152". Granules in parallel 

 rows. 



H. Polycystinorum (E.). — Angles ex- 

 tended into very long, narrow, linear, 

 horn-like processes, which are attenuated 

 at the extremity, and, as well as the base, 

 ceUulose. EM. pi. 3G. f. 43. Barbadoes 

 deposit. Between the processes are from 



one to three slight projections ; lateral 

 view oval, bordered, having transverse 

 bars corresponding in number to the de- 

 pressions. 



H. ? Australis (E.). — ^Valves strongly 

 granulate ; lateral processes rounded, 

 intermediate one obsolete. KSA. p. 139. 

 Antarctic Sea. 



H. ? Californicus (E.). — Valve granu- 

 late, having a subquadrate base ; angles 

 extended into linear processes without 

 intemiediate projections. EM. pi. 33. 13. 

 f. 15. In Califomian tripoli. 



Genus ISTHMIA (Ag.). — Frustules compressed, trapezoidal, ceUulose, 

 attached, cohering by short neck-like processes, so as to resemble irregularly 

 branched filaments. Frustules always more or less oblique, the lower angle 

 of each prolonged into a process by which it coheres to the one beneath, and 

 which in the basal frustule forms the stipes by which the filament is attached. 

 The fi^ustules are tui"gid, and the reticulations of the central portion smaller 

 than those of the sides. 



IsTHinA enervis (E.). — Lateral valves 

 with large, somewhat quadrate cellules 

 arranged in transverse parallel lines. 

 = Cmiferva ohliquata, EB. t. 1869; I. 

 obliquata, Ag. ; I. nei'vosa, KSA. p. 135 ; 

 E Inf. p. 209; pi. 16. f. 6 ; SBD. ii. p. 52, 

 pi. 48. Europe, America, Cape of Good 

 Hope, &c. (x. 183.) The lateral por- 

 tions are separated from the central one 

 by rather broad lines, produced by the 

 junction and inflection of the margins, 

 and which form internally projecting 

 plates or rims. The cellules bordering 

 the sutures are somewhat larger than 

 the other cellules of the central portion, 

 but less remarkably so than in the next 

 species. 



I. nervosa (K.). — Lateral portions with 

 parallel transverse costse, having two or 

 more series of hexagonal cellules in each 

 interval. = Diatoma obliquatmn, Lyng. ; 



I. obliquata, E. ; I. nervosa^ KA.. 135 ; 

 SD. ii. p. 52, pi. 47. Northern shores of 

 Europe and America. This is usually a 

 more northern species than /. enervis. 

 The cellules are smaller, except a series 

 of large conical ones bordering the inner 

 side of the sutures, and the frustules are 

 generally not so wdde in proportion to 

 their length; but the most evident di- 

 stinction is the division of the lateral 

 portions into compartments by the costse, 

 which often anastomose. 



I. minima (Harv. & B.). — Central por- 

 tion very finely decussately punctated; 

 lateral portions granulated by large 

 cellules. Proc. of Acad, of Phil. Rio 

 de Janeiro and Sooloo Sea. 



Imperfectly known. 



I. ? Africana (E.). — Large flat frag- 

 ments resembling the central portions of 

 3i2 



