NOVARA DIATOMS. 77 



rupted by an elliptical ring similar to a form figured by Greville as 

 P. elongation, and which does not reach the margin of the valve. 

 PL v. fig. 4 a. b. 



P. constxictum var. .' Nankoorensis, Grun. — Valve broad, deeply 

 constricted, central space annular. PI. v. fig. 9. 



The transformation of the two central costa? of Plagiogramma 

 into enclosed elliptical and round rings clearly indicates the neces- 

 sity of uniting Glfiphodesmis with Plagiogramma. 



Our form is distinguished from P. constrictum by the form 

 of the terminal smooth spaces which are longly elliptical, whilst in 

 Greville's figure the lower part of the nodule has a flat base. 



(I am unable to agree with the author's remarks that Plagio- 

 gramma and Glyphodesmis should be united; the latter genus has 

 a distinct central nodule, in Plagiogramma this is wanting. — F. K.) 

 Denticula nicobarica, Grun. — Small, valves narrow, linear, some- 

 times linear lanceolate, rounded at the apex, costae 12 to 14 in. 

 •001, striae granular, 24 to 28 in. -001. PL v. fig. 6, a. valve, b. 

 frustule. Not uncommon in the " Polycystin stone" from Nan- 

 koori. 



A characteristic species with conspicuous moniliform striae 

 between the costae, and occasionally with interrupted or imperfect 

 costae. 



(This form seems to me to be identical with the Eunotia Sancti- 

 Antonii of Ehrenberg's mikrogeologie and the Denticula Lauta 

 of Bailey in Smithsonian Contributions. A very common form in 

 the Californian deposits. — F. K.) 



Rhaphoneis Rhombus, Ehr. var. dubia, Grun.— Valve broad, 

 ovato-lanceolate ; apices slightly produced, somewhat obtuse ; 

 median line narrow in tlTe central part, slightly dilated ; central 

 nodule obsolete, sometimes slightly visible ; stria 1 punctate, radiant, 

 24 in. -001 ; punctae minute, confluent. PL v. fig. 7. 



Synedra Nitzschioides, Grun.— Small variety ; valve marked on 

 both sides with cuneate, marginal puncta, 30 to 32 in. *001. PL v. 

 fig. 8. a. b. c. d. 



On Algae from- Valparaiso. 



Many of the valves are slightly cuneiform, and resemble the more 

 delicate and short wedge-shaped frustules of Meridian marinum, 

 Greg., which I found in detached frustules in shore sand from 

 Auckland, and which I atone time took to be a Sceptroneis. 



(I am unable to detect any resemblance to the genus Xitzsehia, 

 at least as that genus is usually understood. Judging from 

 Grunow's figures I should refer this form to Denticula, possibly a 

 variety of D. mutabile.—F. K.) 



Nitszchia panduriformis, Greg. Var.? Nicobarica. Grun.— 

 Valves large, irregularly granulate ; granules minute; transverse 

 striae delicate ; longitudinal striae obsolete; oblique none ; puncta 

 on keel large. PL v. fig. 5. 



In sea sand from the island of Kamortha. 



