162 CONJUGATED. 



terminate by the discovery of a specimen in which perfect 

 sporangia were formed. The filaments, when dried on paper, 

 exhibit less gloss than the other species of the genus, and the 

 endochrome contracts but little. When the sporangia are 

 formed, but little difference can be detected between its fila- 

 ments and those of the following species. Where the species 

 does occur, it is ordinarily very abundant, destroying most 

 other Conferv<2 with which it is in contact, by its more vi- 

 gorous growth. The highly developed mucous sheath, which 

 is so characteristic of the sj^ecies, frequently presents waived 

 and irregular margins. 



3. Tyndaridea lutescens Hass. 



Plate XXXVIII. Fig. 4. 



Char. Filaments of nearly the same diameter as those of the 

 preceding species. Cells at first scarcely so long as broad, 

 a?id filled with endochrome; sxd)seqiiently they become longer 

 than broad; and then the endochrome j^resents a partial 

 division, each division being somewhat stelliform. Sporangia 

 circular. 



T. cruciata Harv. in Manual, p. 141. 



Hab. Cheshunt and its vicinity : A. H. H. 



This is the species which until lately I have regarded as 

 the Conjugata cruciata of Vaucher, to which in all, save 

 size, it bears considerable resemblance. It appears to be the 

 commonest species of the genus ; but I am not able to refer 

 it to any of Vaucher's species. Tyndaridea abbreviata, An- 

 nals of Nat. Hist., vol. X. p. 43, I am now inclined to think 

 is but this species with cells shorter than ordinary. 



4. Tyndaridea bicornis Hass. 



Plate XXXVIII. Fig. 5. 



Char. Filaments more slender than those of the preceding 

 species. Endoclirome divided iiito two masses, which are 

 united by a narrow band in the centre, each mass present- 

 ing two -points or horns on its distant extremity. Sporangia 



