44 CHORDARIACEiE. 



Parasitical on Alaria esculenta. Annual. Summer. Fronds J to | inch 

 long, straight, growing in stellate tufts, scattered over the surface of the 

 leafy portion of the Alaria, tapering from a widish base to a Munt point, 

 dull olive-brown. 



ORDERS. CHORD ARFACE^. 



Chordariese, Harv. in Mack. FL Hib. part 3, p. 183. 

 Man. p. 45. J. Ag. Sp. Alg. p. 45. Chordarieae (excl. gen.), 

 J. Ag. Alg. Medit. p. 31. Endl. 3d Supp. p. 23. Due. Ess. 

 p. 33. Mesogloiaceae, Kiltz. Phyc. Gen. p. 329. Chordari- 

 dse (excl. gen.), Lindl. Veg. King. p. 22. 



DIAGNOSIS. Olive-coloured sea-weeds, with a gelatinous 

 or cartilaginous frond, composed of vertical and horizontal 

 filaments interlaced together. Spores attached to the fila- 

 ments, concealed within the substance of the frond. 



NATURAL CHARACTER. Root in the more perfect kinds a 

 conical disk, in others forming the under surface of a crusta- 

 ceous frond. Frond very variable in form, in all cases com- 

 posed of articulated threads, variously combined together, 

 lying in a transparent gelatine of rather firm consistence. 

 This gelatine is sometimes in small quantity, and then the 

 fronds are firmly coriaceous : but more generally the gelatine 

 is abundant, causing the threads to lie separate one from 

 another, and giving to the substance of the frond either a car- 

 tilaginous and elastic or a soft and gelatinous nature. The 

 least organized genus of this family (Ralfsia) has a crustaceous 

 frond, spreading over the surface of rocks in circular or ob- 

 long patches, and bearing on its surface small prominences, 

 which eventually contain spores. Next to this in develop- 

 ment is Leathesia, whose frond is either shapeless or variously 

 lobed, resembling small tubers heaped together. This genus 

 is closely allied in structure to Mesogloia, whose frond as- 

 sumes a branching, more or less regularly pinnated habit ; 

 and in Chordaria we reach the greatest compactness and 

 composition that our waters supply. A further advance, 

 however, is found in the genus Scytothamnm of New Zea- 

 land, where the frond, still clearly consisting of filaments 

 lying in gelatine, is so firmly knit together as to resemble in 

 substance one of the FUCACE.E. Elachistea and Myrionema 

 are somewhat abnormal in character, partaking in much of 



