Ser. Melanosperme,e. Fam. Chordariea ? 



Plate XXVIIL (A). 



ELACHISTEA ATTENUATA, Raw. (ap.no*.) 



Gen. Char. Parasites composed of simple, vertical, or radiating, jointed 

 filaments, issuing from beneath the surface-cellules of other Algae ; 

 the lower part of the filaments hyaline and compacted together into 

 a tubercle, the upper-half coloured (olive), free. Spores oblong, 

 mostly stalked, affixed to the bases of the free portion of the filaments, 

 or to the tubercular base. Elachistea {Duly) — seemingly from 

 i\dxi(TTa } the least. 



Elachistea attenuate/,; tufts very minute, globose; filaments fusiform, 

 much attenuated toward both ends, the basal joints 3-4 times, the 

 middle once and a half, the apical about as long as broad ; spores 

 linear-obovate, subsessile at the base of the filaments. 



Hab. Parasitical on the fruiting branches of Cystoseira ericoides. Annual. 



Summer and Autumn. At Elberry Cove, Torbay, Sep. 1844, Mrs. 



Griffiths and W.H.H. 



Geogr. Distr. South of England. 



Descr. Tufts half a fine to nearly a line in diameter, spherical, originating in a 

 minute tubercle, which extends its roots (or bases of its filaments) into the 

 substance of the Cystoseira. Filaments from a quarter to nearly half a 

 fine in length, thickened in the middle, tapering greatly to either end, 

 obtuse, jointed. Lower articulations nearly colourless, slender, cylindrical, 

 3-4 times longer than broader; middle articulations sub-elliptical, con- 

 tracted at the dissepiments, once and half as long as broad, containing a 

 bag of bright olive granular endochrome ; upper articulations gradually 

 shorter upwards, and gradually monihform towards the apex. Spores 

 abundantly produced at the base of the filaments, narrow obovate, dark 

 olive, with a wide limbus. 



In a delightful excursion, made in the autumn of 1S44, in 

 company with my valued friend Mrs. Griffiths, to visit the habi- 

 tat of Gigartina Teedii at Elberry Cove, we observed that most 

 of the fronds of Cystoseira ericoides, which grows in great luxu- 

 riance on an exposed rock in the cove, were infested with the 

 minute parasite here represented. The size and shape of the 

 filaments readily distinguish it from any of the Bril ish Elachistea ; 

 but in these characters it agrees with /:'. rivularia, Suhr., from 

 which it is chiefly distinguished by the globose form of the tuft. 

 E.rivularice, which also inhabits Cystoseirce, and will probabl] 



ii 2 



