ON STENOGRAMME INTERRUPTA. Harv. 

 Bij E. M. Holmes. 



The tetrasporic fruit of this rare and beautiful alga has not 

 liitherto been recorded as occurring in Britain, and is not described 

 in any of the more recent works on marine algte published in Eng- 

 land, nor has any figure of the tetraspores, so far as I am aware, 

 ever been published. A description, with explanatory cuts of these 

 may therefore be interesting to British Algologists. Miss Giffojd, 

 of Minehead, Somerset, the author of the " Marine Botanist's 

 Guide," appears to have been the first who met with Stenogramme 

 having sori of tetraspores. A specimen sent by that lady to Dr. 

 Harvey in 1848, with an enquiry as to the nature of the spores, 

 was probably lost, as no further notice of the plant was taken by 

 him. In 1851 specimens with tetraspores were collected by the, 

 late Dr. Welwitsch, in the Tagus, near Lisbon, and sent to Dr. 

 Montague, of Paris, who carefully examined them, and sent a letter 

 describing the tetraspores to that veteran cryptogamist, the Rev. 

 M. J. Berkeley, who published the letter in the " Ann. and Mag. of 

 Nat. Hist.," June, 1851, p. 481. This description appears to have 

 been overlooked by most British algologists up to the present 

 date. 



My attention was lately drawn to the plant by the occurrence of 

 a specimen with tetraspores in Mr. Carroll's collection, recently 

 acquired by the British Museum. Through the kind permission of 

 Mr. Carruthers, I was permitted to examine the plant, and being 

 at that time unaware that the tetraspores had been described, made 

 a memorandum of their appearance and structure, which was after- 

 wards found to correspond almost exactly with the description 

 given in Webb's " Otia Hispanica," p. 16, published in 1853. As 

 his description is extremely miniite, it will be well to quote it : — 



Tetraspores arranged in oval or oblong nemathecia, which are 

 scarcely a line in length, often less. The nemathecia are convex 

 when moist, becoming flattened when dry, and scarcely visible above 

 the surface of the frond, from which they can then be distinguished 

 only by their darker colour. They are generally scattered over the 

 surface of the frond, or more rarely arranged in two parallel lines ; 

 occasionally two nemathecia become confluent. The nemathecia 

 consist of a number of vertical or slightly radiating filaments, each 

 consisting of about 4 cells (fig. 3, «), these filaments being formed 

 by the multiplication of the small surface cells of the frond ; the 

 endochrome of each cell becoming divided — first tiansversely (fig. 

 3,6), and then longitudinally (fig. 3, c, (I) — thus forming cruciate 

 tetraspores. The tetraspore are oblong, narrow, and very small 

 for the size of the plant. When the tetraspores fall away a pale 

 (?pot (which is an opening in the frond) is left, owing to the tetra- 

 spores having been formed at the expense of the layer of surface 

 cells, as above described. 



