STEPHANOCEROS. 



[ 615 ] 



STEREOCAULON. 



middle of the body; nucleus moniliform. 

 Length 1-24". 



Five other species. 



Dujardin places this genus in the family 

 Urceolarina. 



BIBL. Ehrenberg, In/us. 261; Stein, 

 Infus. passim. 



STEPHANOCEROS, Ehr. A genus of 

 Rotatoria, of the family Flosculariaea. 



Char. Eyes single; rotatory organ divided 

 into five tentacle-like lobes, furnished with 

 whorls of vibratile cilia ; body attached by 

 the base to a cylindrical hyaline carapace. 



S. Eichhornii (PL 35. fig. 25). The only 

 species. Aquatic ; length 1-36". This beau- 

 tiful animal uses the lobes of the rotating 

 organ to catch its prey, in the manner of 

 Hydra. At a (fig. 25) are seen the tremu- 

 lous bodies, above which is a row of round- 

 ish globules, called by Ehrenberg nervous 

 ganglia. 



BIBL. Ehrenberg, Infus. 400. 

 ' STEPHANOD1SCUS, Ehr. A doubt- 

 fully distinct genus of Diatomaceae. 



Char. Frustules discoidal, single ; valves 

 circular, alike, not areolar (under ordinary 

 illumination), and with a fringe of minute 

 marginal teeth. Aquatic. 



S. berolinensis has the valves finely 

 radiate, with mostly thirty-two teeth, 

 and is 1-1150'' in diameter; whilst in S. 

 Niagara the centre of the valves is granular, 

 the circumference radiate, the teeth sixty- 

 four, and the diameter 1-430". 



These species should be referred to Cos- 

 cinodiscus or Cyclotella. 



BIBL. Ehrenberg, Ber. d. Berl. Akad. 

 1845. Ixxii.; Kiitzing, Sp. Ala. 21. 



STEPHANOGONIA, Ehr. An obscure 

 genus of fossil Diatomaceae. 



Char. Frustules resembling those of Mas- 

 togonia, but with the apices of the valves 

 truncate, angular, and spinous. 



Two species found in Bermuda and North 

 America. 



BIBL. Ehrenberg, Ber. d. Berl. Akad. 

 1844. 264 ; Kiitzing, Sp. Ala. 26. 



STEPHANOPS, Ehr. A genus of Rota- 

 toria, of the family Euchlanidota. 



Char. Eyes two, frontal, foot forked ; 

 carapace depressed or prismatic; anterior 

 part of body expanded so as to form a frontal 

 hood. 



Jaws each with a single tooth. 



S. cirrhatus (PL 35. fig. 28). Carapace 

 with two posterior spines. Aquatic ; length 

 L240". 



S. muticus has the carapace without spines 



posteriorly, and the eyes have not been 

 recognized; whilst S. lamellatus has three 

 posterior spines. 



BIBL. Ehrenberg, Infus. 478. 



STEPHANOPYXIS, Ehr. = Pyxidicula, 

 a genus of Diatomaceae. 



S. diadema=Pyxidicula diadema. 



As Pyxidicula is passed over in its 

 proper place, we may take the opportunity 

 of inserting it here. Its characters are : 



Frustules single, free or sessile; valves 

 circular, convex, hoop absent ! 



Twenty-two species have been described, 

 one aquatic, one marine, the remainder 

 fossil, found in America. Some of them do 

 not appear to differ from Coscinodiscus, 

 except in the greater convexity of the valves. 



P. major (PI. 19. fig. 13). Valves conical, 

 regularly punctate. Diameter 1-420". Aqua- 

 tic. 



P. adriatica. Frustules sessile ; valves 

 almost hemispherical, free from markings 

 (ordinary illumination). Upon marine algae, 

 diameter 1-600". 



P. minor, K. Frustules spherical, with 

 two median parallel furrows. 



This appears to be the P. operculata of 

 Ehrenberg, which Kiitzing considers to be 

 the same as his Cyclotella operculata. 



The bodies represented in PL 19. fig. 12, 

 found in flint, have been described as P. glo- 

 bator, Pritch. (not P. alobosus, E.) ; they 

 do not appear, however, to belong to the 

 Diatomaceae. 



See also XANTHIOPYXIS. 



BIBL. Ehrenberg, Infus. p. 165, Ber. d. 

 Berl. Akad. 1844 & 1845 ; Kiitzing, Bacill. 

 51, Sp. Ala. xxi. ; Pritchard, Infusoria, 432. 



STEPHANOSPILERA, Cohn. A genus 

 of Volvocineae (Confervoid Algae), not yet 

 observed in Britain. S. pluvialis is related 

 to Volvox, consisting of a large hyaline globe 

 with eight biciliated green cells, placed at 

 equal distances on the equator. 



BIBL. Cohn, Sieb. fy Kollik. Zeitschr. iv. 

 p. 77 (1852) (Ann. Nat. Hist. 2nd ser. x. 

 p. 321. pi. 6). 



STEREOCAULON, Ach. A genus of 

 Lecidineae (Gymnocarpous Lichens), so 

 called from the solid character of the 

 branched bushy thallus. S. paschale, the 

 most distinct species, is abundant on rocks 

 and stones on mountainous districts. The 

 thallus is grayish and rough, the apothecia 

 conglomerated, blackish-brown. The sper- 

 inogonia occur in little brown heads, near 

 the apothecia. 



BIBL. Hook. Brit. Flor. ii. pt. 1. p. 237; 



