OF THE N-AYICULE.E. 



923 



roiinded ends, and a longitudinal row of 

 undulations on each side. BC. ii. p. 38, 

 pi. 2. f. 15 & 23. America. Often 

 twisted. " The ruffle-like rows of pin- 

 nules distinguish this species from all 

 others" (Bailey). 



Doubtful Species. 



A. recta (Greg.). — Front ^dew qua- 

 drangular, with rounded angles and very 

 slightly constricted sides ; striae fine but 

 distinct. TM. v. p. 67, pi. 1. f. 40. Scot- 



land. The figure presents no appearance 

 of alae, but only convex lateral valves, 

 such as are seen in several species of 

 Navicula. 



A. navicularis (E.). — Oblong, with 

 obtuse ends and radiant transverse stride ; 

 front view quadrangular, with two 

 pimcta at each end. EA. p. 122 ; EM. 

 several figures. Fresh water. America. 

 Apparently a Na\'icula with the ter- 

 minal puncta of the front view less mar- 

 ginal than usual. 



Genus DIADESMIS (Kiitz.).— Frustules navicular, united into a filament; 

 valves with central and terminal nodules. Habit of Fragilaria, but the valves 

 furnished with median line and central nodule. Diadesmis differs from 

 Sphenosira only in having the lateral siurfaces with similar ends. 



* Freshwater or Fossil. 



Diadesmis confervacea (K.). — Breadth 

 of articulations twice the length ; valves 

 minute, smooth, with acute, acuminate 

 ends. KB. p. 109, pi. 30. f. 8. Trinidad. 

 (XIV. 32, 33.) 1-960". 



D. Icevis (E., K.). —Smooth; breadth 

 of articulations three to four times the 

 length. KB. p. 109, pi. 29. f. 69. = T«Je/- 

 laria Icevis, EA. pi. 1. 2. f. 17. Chili, 

 (xii. 40.) 



D. sculpta (E., K.). — Articulations 

 with striated margins ; valves linear- 

 oblong, with roimded ends and a narrow 

 sti-iated border. IvB. p. 109, pi. 29. f. 26. 

 = TaheUaria sculpta, EA. pi. 1. 2. f. 6. 

 Chili. Resembles Navicula horealis, E. 



D. ? Bacillum (E., K.). — Articulations 

 striated, linear-oblong, with rounded 

 ends, and a large, oblong, longitudinal 

 median nodule. KB. p. 109. = Navicula 

 Bacillum, E. Fossil. Greece. 



D. Navicula (E.). — Frustules oblong, 

 smooth, four or five times as long as 



broad, with a smooth median stiicture. 

 = Fragilaria ? Navicula, EA. p. 127, 

 pi. 1. 3. f. 8. Peru. We place this form 

 in Diadesmis because the frustules, in 

 the front view, have a minute punctum 

 at the middle of each lateral margin, — 

 an appearance which usually indicates 

 the presence of central nodules. 



D. Gallica (S.). — Filaments straight 

 or curved ; valves linear-elliptical, with 

 about 45 obscure striae in -001". Sm. 

 ANH. Jan. 1857, p. 11, pi. 11. f. 16. 

 Havre. 



D. peregrina (S.). — Victoria tank, Glas- 

 gow. This species is unknown to us. 



2* Marine. 

 _ D. WilUamsoni (S., Greg.), — Front 

 \aew linear, with central and terminal 

 dilatations; valves linear, with attenuated 

 ends and 16 to 18 dotted sti'iae in -001. 

 GDC. p. m, pi. 2. f. 40. = Himcmtidium 

 Williamsoni, SBD. ii. p. 14, pi. 33. f. 287. 

 Marine. Scotland. 



Genus STIGMAPHORA (WaUich). — Frustules free, naviculoid ; valves 

 lanceolate, loculate ; loculi with central and marginal puncta. Marine. 

 Frustules very hyaline, with two minute cells at the midcHe of each margin 

 in both views ; valves with median line. 



Stigmaphora rostrata (Wallich). — 

 Valves rostrate ; beaks with a median 

 row of puncta. TM. viii. p. 43, pi. 2. 

 f. 5, 6. (Yiu. 48.) India. 



S. lanceolata (Wallich). — Valves 

 acutely lanceolate, without median rows 

 of puncta. TM. viii. p. 43, pi. 2. f. 7, 8. 

 India. 



