July 1, 1S67.] 



HARDWICKE'S SCIENCE-GOSSIP. 



157 



Navicula ssrians (Kutzing), Valves acute with 

 two sets of stria, longitudinal, distinct, about 30 in 

 100, under a low power apparently undulate, trans- 

 verse striae delicate, about 50 iu 100 ;(fig. 155). 

 Common in this material. 



Variety a (apiculate), varying from lanceolate- 

 elliptic to rhomboid, with apices more or less pro- 

 duced, and capitate (Lewis). This form I have not 

 yet detected in the deposit ; variety /3 (cruciform) = 

 Navicula follis = Navicula trochus? = Navicula in- 

 flata (Ehr.) ? Valves much inflated, compressed, 

 sloping abruptly towards the produced apices 

 (Lewis) (fig. 156). Navicula follis and Navicula 

 trochus are no doubt identical; and that this variety 

 is identical with it is equally certain. Common in 

 this deposit. 



Navicula rhomboides (Ehr.), Valves nearly quad- 

 rangular, .stria; faint, parallel, 85 in 100 j (Smith) 

 (fig. 157). Variety a of Lewis does not occur in 

 this deposit. Variety /3 = Navicula diaphana (Ehr.), 

 Valves lanceolate, extremities slightly obtuse, 

 median line terminating in an 

 obtuse rounded nodular expan- 

 sion, striae transverse, about 55 

 to 60 in 100 ; longitudinal striae 

 coarser, slightly wavy, about 45 

 in 100, more or less indis- 

 tinct about the central nodule 

 (Lewis) (fig. 15S). This and 

 var. a are considered to be 

 sporangial varieties of the 

 typical Navicula rhomboides, 

 not uncommon in this deposit. 



m 



Fie:. 15;. 

 Navicula rhomboides, Ehr. 



Fig. 158. 

 Navicula rhorr.boides, var. R. 



Stauroneis Baileyi = (Ehr.), valves large, broadly 

 lanceolate, tapering gradually to the obtuse apices ; 

 surface with very firm longitudinal wavy lines, 

 stauros linear reaching the margin (Kutzing). In 

 the Microgcologie of Ehrenberg are many figures of 

 this form, and Stauroneis Phcenicenteron ; but, on 

 careful examination, it is not at all clear what 

 Ehrenberg means. S. Phcenicenteron has fine trans- 

 verse striae, and a slightly dilated stauros, but not 

 the wavy longitudinal lines. Ehrenberg, however, 

 gives a figure of a form with a dilated stauros and 



distinct wavy lines, which he calls Stauroneis 

 Phcenicenteron (Baileyi), (sic) ; thus mixing up the 

 two species. Dr. Lewis at one time supposed that 

 this was a sporangial variety of Stauroneis acuta ; 

 but from further observation he has come to the 

 conclusion that Stauroneis Baileyi and Stauroneis 

 pteroidea arc interchangeable varieties of a com- 

 mon species, probably Stauroneis Phoenicenteron. 

 (Eig. 159), fig. b, under surface, showing a siliceous 

 plate at the apex of valve ; fig. c, ideal section of 

 same at d, showing vacant space between valve and 

 plate. 



e^§? ~-~ 





b. Under surface. 









\ ~ -" 









c<^J 



Mi 



Fisr. 159. Stauroneis Baileyi 

 (upper surface), x 400). 



Fig. 160. Stauroneis 

 legumen, x 500. 



Stauroneis legumen (Ehr.), this form (fig. 160) is 

 considered by Dr. Lewis to be an aberrant variety of 

 the above species — not uncommon in this deposit. 



Eunotia septena (Ehr.), fig. 161, is a variety of 

 Eunotia robusta. Eunotia camelus (Ehr.), fig. 162 ; 

 this species varies much in outline, and is probably 

 only Himantidium bidens. Eunotia bactriana 

 (Ehr)., fig. 163; all the above are common in this 

 deposit. 



