318 ARCHER^ OX A NEW SPECIES OE COSMAKIUM. 



it Avith any other.* It is intermediate in size between C. 

 hioculatinn and C. tinctum ; but, besides the tubercles, it is 

 quite distiuet from tliera by its broader isthmus and more 

 broadly elliptie segments. 



Genus — Staurastrum, Meyen. 

 Staurastrum lanceolatum, sp. nov. 



Specific characters. — Frond minute ; segments smooth, 

 broadly laneeolate, extremities aeute, minutely apieulate ; end 

 view triangular, angles minutely apieulate, sides eoneave. 



Locality. — Sphagnum ponds. Featherbed bog, county of 

 Dublin, coating the moss. 



General description. — Frond minute, about as broad as 

 long, constriction forming a deep, acute notch at each side ; 

 supposing the constriction absent, the frond would present an 

 orbicular outline; segments smooth, in front view broadly 

 lanceolate, the outer margin slightly more convex than the 

 inner, their opposite lateral extremities acute, minutely api- 

 eulate (though the apiculus is sometimes difficult of detection) ; 

 end view triangular, angles somewhat inflated, minutely api- 

 eulate, sides concave at the centre. Sporangium orbicular, 

 spinous; spines numerous, somewhat inflated at the base, 

 their extremities subulate, acute. 



Measurements. — Length of frond, ^ „ \ „ ; breadth, -rriVo ; 

 diameter of sporangium, including spines, -^^i-g^; not including 

 spines, — tVtt of an inch. 



Plate XII, fig. 16, front view; fig. 17, angular view; fig. 

 18, end view; fig. 19, dividing frond; figs. 20, 21, 22, con- 

 jugating fronds; fig. 22, showing mature sporangium. All 

 magnified 400 diameters. 



Affinities and differences. — This species agrees somewhat 

 with Staurastrum orbicidare, Ralfs, in its general external 

 outline; but it differs therefrom in its segments being lanceo- 

 late, not semiorbicular (the constriction lacing not linear, 

 but a gaping notch), and in the opposite lateral extremities 

 not being rounded, but acute and apieulate. Its lanceolate 

 apieulate segments separate it from S. muticum, Breb. The 

 same characters separate it from S. FyynKEum, Breb., which 

 latter has cuneiform segments, as well as the extremities of 

 the spines of the sporangium being bifurcate, not subulate 



* Unfortunately the flgures (figs. 11 — 14) arc incorrect in representing 

 the tubercles as so large and elevated. They do not stand out, nor do they 

 appear of the nature of the " pearly granules " of other species. They are 

 more minute, less elevated, and more opaque than in the figure. 



