EUASTEUM. 



[ 304 



genus Kiitzing refers Hivulann jylicata, atra, 

 and perhaps applunata of Harvey. These 

 plants are interesting- on account of the 

 fibrous decomposition of the gelatinous 

 sheaths. 



BiBL. Harvev, Brit. Mar. Alg. 222, pi. 

 26 A (Rimtlarici) ; Kiitzing, Sp. Alg. 339 ; 

 Tab. Ihi/c. cent. ii. pis. 74-82. 



EUAS'TRUM, Ehr.— A genus of Des- 

 midiacese. 



Char, Cells single, compressed, deeply- 

 divided into two segments, which are gene- 

 rally pyramidal and fm-nished with circular 

 protuberances, lohed or sinuated at the mar- 

 gins, and emarginate at the ends. 



Ralfs desciibes twenty-one British spe- 

 cies, of which the following are the most 

 common. 



* Segments deeply lohed; end lobe distinct, 

 cuneate, partly included in a notch be- 

 tiveen the lateral lobes. 



E. verrucosum (PI. 14. fig. 14). Rough ; 

 segments three-lohed, lobes broadly cuneate, 

 with a shallow notch ; length 1-2G7". 



E. ohlongum (PI. 14. fig. 15). Smooth, 

 oblong ; segments five-lobed ; lobes cmieate ; 

 emarginate; length 1-156". 



E. crassum. Smooth ; segments three- 

 lubed, subquadrilateral ; end lobe cuneate ; 

 length 1-190 to 1-130". 



** Segments simtated ; end lobe exserted and 

 united with the basal po7'tion by a distinct 

 nech. 

 E. didelta (PI. 14. fig. 16; 17, empty 

 cell). Segments with inflated base, inter- 

 mediate tubercles, and notched and scarcely 

 dilated ends; side view, four shallow lateral 

 lobes, and one at each end ; length 1-185". 



*** End lobe indistinct ; frequently a process 

 or acute angle at the corners of the ter- 

 minal portion. 



E. elegans. Oblong ; ends emarginate, 

 pouting, and roimded ; length 1-890 to 

 1-420". 



Conjugation has been observed in several 

 species ; the sporangia are spherical, _ with 

 conical tubercles, or acute or obtuse spines. 



BiBL. Ralfs, Brit. Desmid. 76; Raben- 

 horst, Fl. Alg. iii. 179. 



EUCAM'PIA, Ehr. — A marine organism, 

 allied to the l)(\smidiace?e, among which it 

 is placed by Kiitzing, whilst Smith refers it 

 to the Diatomaceaj. 



It forms articulated, arcuate or spiral, 

 fasciteform, microscopic fronds, composed 



] EUCHLANIS. 



of hyaline wedge-shaped frustules, with 

 yellowi>h granular contents. Tlie joints 

 shrink in drying, and are destroyed by heat. 

 The marldngs consist of dots. 



E. zodiacus (PL 50. fig. 10). Frustules 

 with a median excavation on each side ; 

 valves elliptical; length 1-710". 



E. britannica. Frustules not excavated ; 

 length 1-380". 



E. striata. Valves circiUar ; endochrome 

 green. 



BiBL. Ehrenb. Ab7i. Berl. Ak. 1839, 125; 

 Kiitzing, Sp. Alg. li>l, Bacillar. pi. 21. fig. 21 ; 

 Smith, Br. Dint. ii. 25 ; Stolterforth, Jn. M. 

 Soc. 1879, ii. 835. 



EUCERTYDTUM, Ehr.— A genus of 

 Polycystina. 



E. ampulla (PI, 39. fig. 25, front view ; 

 fig. 26, imder view). 



See POLYCYSTIXA. 



EUCIILAJS^IDO'TA, Ehr.— A family of 

 Rotatoria. 



Char. Rotatory organ multiple, or divided 

 into more than two lobes ; a carapace pre- 

 sent. 



The carapace forms either a testa or a 

 scutellum ; various appendages are present, 

 representing either straight bristles, cm'v-jd 

 bristles or hooks, minute horns — so-called 

 respiratory tubes or antennae, — and in one 

 genus a frontal hood. 



The eleven genera are thus distinguis^^ed : 



Eyes absent; foot forked ^ Sf/ff 



Eyes present. 

 Eye single (cervical). 

 Foot styliform. 



Carapace depressed Jlononfyla. 



„ prismatic Alastigocerca. 



Foot forked. 



Carapace open beneath Euchlanis. 



„ closed beneath. 



Carapace with horns Salpina. 



,. without horns Diiwcharis. 



Eyes two (frontal). 



Foot styliform Moyioctrca, 



„ forked. 



Carapace compressed or prismatic. Cohtrus. 

 „ depressed or cylindrical. 



Head without a hood Metopidia. 



„ with a hood Siejihanops. 



Eyes four; foot forked Squaiiiella. 



BiBL. Ehrenb. Itifus. p. 455. 



EU'CHLANIS, Ehr.— A genus of Rota- 

 toria, of the family Euchlanidota. 



Char. Eye single, cervical ; foot forked ; 

 carapace cleft or open on the ventral surl'ace. 

 Aquatic. 



Ehronberg describes six species, to which 

 Gosse adds three. 



E. triquetra (PL 43. fig. 30; fig. 31, teeth). 

 Carapace very large, with a dortal crest; 

 foot without setae ; length 1-48". 



