OF THE MELOSrRE.E. 



823 



a lagoon at Manfredonia, east coast of [ late, but requires the highest magnify- 

 Italy. Each tooth is minutely denticu- | iug powers to ascertain it. (v. Q8.) 



Genus LIPAROGYRA (Ehr.).— Fnistiiles simple, cylindrical, each having 

 an internal spiral filiform band or crest. 



The habit of this genus closely resembles that of Spirogyra, a non-silicious 

 genus of Algae. 



LiPAROGYBA dendroteres (E.). — 

 Frustules smooth, ciystalline, three or 

 fom- times as long as broad, with an 

 internal spiral band j margin of disc 

 denticulated. Rab D. p. 12. =L. spircdis, 

 EM. pi. .34. 5 a. f. 1, 3. On ti'unks of 

 trees. Venezuela. Thirteen spii'als in 

 1-360". (v. 72.) 



L. circidaris (E.). — Frustule witli 13 

 annidar tiutis of internal line in 1-360". 



Rab. /. c. p. 12. With the preceding, and 

 in Brazil. Ehrenberg says he is not 

 satisfied whether the preceding are di- 

 stinct species, or merely varieties. Each 

 has a smooth disc, with three central 

 apiculi. 



L. scalaris, EM. pi. 34. 5 a. f. 2. South 

 America. Ehrenberg's figure represents 

 the frustide in fi"ont view as divided by 

 cross bars in a ladder-like manner. 



Genus POROCYCLIA(Ehr.). — Resembles Liparog}Ta, but is without spii-es, 

 has interior circular rings, and the margin of its disc-like ends a circlet of 

 deep impressions. We doubt whether this genus is sufliciently distinct from 

 Liparogyra. 



PonocYCLiA dejidrophila (E.). — 

 Frustides smooth, with 9 annular lines ; 

 disc with 12 marginal depressions. 



radiating series of puncta, and 5 central 

 apicidi. RabD. p. 12. On tiimks of 

 trees. Venezuela. L. 1-320" ; w. 1-560". 



Genus STEPHANOSIRA (E.).— Fiiistules united into a short filament ; 

 disk with radiating series of minute puncta, and a marginal crowoi of teeth. 

 In form this genus resembles Stephanodiscus, but differs from it, and becomes 

 allied to Melosira by its imperfect spontaneous division, and consequent con- 

 catenation, In Melosira, however, the circlet of spines is wanting. We are 

 unacquainted with this genus ; and its characters scarcely suffice to distinguish 

 it from Orthosira. AU the known species are found on trees. 



Stephanosiba Epidendron (E.). — i 

 Front view with punctated transverse j 

 lines and fmTow. Rab D. p. 14. On trees. , 

 Venezuela and Brazil. Larger diameter ! 

 1-432"; smaUer 1-4320". 



S. Hamcuh'ijas (E.). — In front ^-iew 

 smooth, but with junction-margins stri- 

 ated ; disc having marginal radiating 

 puncta, and its centre a few scattered 

 dots. Rab. /. c. p. 14. On trees with the 



preceding species. Diameter 1-720". 



S. Ewiypcea (E.). — Frustides often 

 broader than long, smooth, but with very 

 faintly striated junction-margins. Rab. 

 I. c. p. 14. Among mosses on trees at 

 Berlin. Much smaUer than the preced- 

 ing. Chain fonned of three to four frus- 

 tides, each 1-2304" to 1-1152" in depth; 

 rarely 1-1200" in width. 



Genus STEPHANODISCUS (E.).— Disc with radiating series of puncri- 

 form granules, and furnished with a crovsTi of erect marginal teeth. Aquatic. 

 Stephanodisci approximate in character to Cyclotella, but differ from them 

 by the circlet of teeth. They also approach closely to the non-cellulose 

 Coseinodisceae, and seem to have as good a claim to rank wdth that family as 

 mth the Melosireae. Stephanodiscus drffers from Odontodiscus in the same 

 manner as Peristephania does from Systephania, and in our opinion might, 

 without inconvenience, be united to it. 



Stephaxodiscus BeroUnensis (E.). ; teeth (often 32) on each side. KSA. 

 — Small, discoid; disc plane, finely radi- i p. 21. Alive, Berlin. Diam. 1-1152'. In- 

 ated, and furnished with acute marginal [ ternal granular substance broA^Ti, lobed. 



