IV. DICTYOTACEJj:.— PuNCTARiA. 115 



1. PoNCTARiA teniiisshna, Grev.; frond very tliin, linear or linear-lanceolate, much 

 attenuated to base and apex, flat or undulated. Grev. Alg. Brit. {18B0) 2^- 54. 

 Harv. Phyc. Brit. t. 248. Punctaria undulata.J. Ag. Sp. Alg. vol. l,p. 72. Dlplo- 

 stromium tenuissimum et D. undulatum, Kutz. Sp. Alg. p. 483. 



Hab. Parasitical on various Alg^ near low-water mark ; as Zostera marina^ Chor- 

 dajilum, c^-c. Annual. Spring and Summer.— Halifax, W. H. H. Boston Harbour, 

 G. B. Emerson. Little Compton, R. I., Mr. Ohey, and Prof. J. W. Bailey. Fort 

 Hamilton, N. Y., Mr. Hooper, ^r., W. H. H. (v. v.) 



This forms dense tufts extending for several inches along the leaves of the Zostera 

 or the fronds of the Chorda on which they grow. T\iq fronds are from two to eight 

 or ten inches in length, and from a line to four or five lines in width, broadest in 

 the middle, and tapering to both extremities. Some specimens are nearly linear 

 throughout, except at the base or apex where they fine off ; but others are strictly 

 lanceolate, very much attenuated from the middle towards the apex and the base. 

 The margin in the young plant is quite flat ; and often remotely, but irregularly 

 denticulate. In older specimens the frond is undulated, or crisped and often twisted 

 spirally. The membrane is very thin, semitransparent, and delicate; and the colour 

 ■which is at first a pale greenish olive, becomes brownish or rather horn-colour in 

 old plants. The fructification has not been observed. 



I retain Dr. Greville's name for this plant, as being of earlier date than that 

 assigned by Prof J. Agardh ; who rejects Dr. Greville's epithet from grounds Avhich 

 appear to me to be insufiicient. The Zonaria tenuissima of the elder Agardh, which 

 Dr. Greville takes as the type of his species, appears to have been founded {Sp. Alg. 

 \. p. 138, and Syst. Alg. p. 268) on Ulva plantaginifolia var. tenuior, Lyngb. Hyd. 

 Dan., p. 31., t. b.; and from Lyngbye's figure and description there can be little 

 doubt that Lyngbye's and Greville's plants were identical in species. Nay, this is 

 admitted by Prof. J. Agardh, who quotes both these authors under his P. undtdata ; 

 but for some cause which I do not understand, he at the same time refers the 

 synonym, " Zonaria tenuissima, Ag." to Laminaria Fascia. Yet, on referring to the 

 Syst. Alg. where that name was first published, and from which Di\ Greville adopted 

 it, we find the only synonym quoted is " Ulva plantagi?iea var. tenuior, Lyngb. t. h." 

 but with a mark of doubt. On referring back to Agardh's earlier work, the Sp. 

 Alg. this same synonym is quoted without any doubt as the authority for Agardh's 

 «' Zonaria plantaginea var. teniuor" which is evidently the type of the subsequent 

 " Z. tenuissima." Whether Agardh confounded young Laminaria Fascia also under 

 this name is not to the point, as it is evident from his description and quotation tluit 

 he intended by the name " tenuissima, " the " U. pihmtaginifoUa var. tenuior " of 

 Lyngbye ; and that is also the plant intended by Dr. Greville, and here described. 

 I see no reason therefore for changing the older and very appropriate specific name 

 into " undtdata." 



2. PuNCTAKiA plantaginea, Grev. ; frond dark brown, coriaceo-membranaceous, 



q2 



