Prof. W. Smith on the Diatomacese of the Pyrenees. 9 



I do not regard these forms as entitled to rank as established 

 varieties of C. lanceolatum, but merely as representatives, at the 

 two extremes, of the multitudinous changes of outline to which 

 this Diatom submits, under climatal and other influences. 



Ehrenberg has erected the second into a distinct species, under 

 the name of C. cornutum : the first, and many of the others, have 

 equal claims to this honour ; but regarding the multiplication of 

 book-species as one of the greatest obstacles to the progress of 

 natural science, I forbear to increase their numbers. 



Plate I. fig. 7- Side view of Cocconema lanceolatum /3. Fig. 8. S. V. of 

 C lanceolatum y. 



Synedra fontinalis, n. sp. Frustules scattered ; S. V. linear- 

 lanceolate, in the smaller specimens elliptical lanceolate ; 

 extremities produced, subcapitate ; nodule indefinite. Striae 

 27 in -001". Length -0006" to -0014". Greatest breadth 

 of valve -00015" to -0002". v.s. 



Fresh water. Spring near the Salut Source at Bagneres de 

 Bigorre. 



Plate I. fig. 9. Synedra fontinalis : a h a\ side views j 6, F. V. of frus- 

 tule in self-division. 



Odontidium hyemale, Kiitz. Synopsis of B. Diatomacese, vol. ii. 

 p. 15. 



Var. p. S. V. linear, extremities rounded. Length of frustule 

 •0013" to -0042". Breadth of valve -0004". v.v. 



Var. 7. S. V. linear-elliptical, contracted towards the linear 

 or subcapitate extremities. Length of frustule -0011" to 

 •0025". Breadth of V. •OOO^. v.v. 



Fresh water. Var. /3. Cambuscou near Cauterets, elevation 

 4920 feet; Pont d'Espagne near Cauterets, elevation 4930 feet. 

 Var. y. Eaux Chaudes, elevation 2296 feet ; Val d'Ossau, elevation 

 2968 feet ; Cascade Gavarnie, elevation 6294 feet. 



Both these varieties occur intermixed with the ordinary frus- 

 tules described in the ' Synopsis,' and with frustules of O. meso- 

 don ; all these appear to be forms of the same species, though 

 the one described as 0. hyemale in the ^ Synopsis ' is by far the 

 most frequent, and is therefore entitled to be regarded as the 

 normal condition of the mature frustule. 



A curiously distorted condition of var. /3, which I have figured 

 in PI. 1. fig. 10 a, occurs in the Cambuscou gathering in tolerable 

 abundance. This variety illustrates the tendency to a repetition 

 of accidental deviations impressed by the self-dividing act, which 

 I have noticed in the Introduction to the Synopsis, vol. ii. p. xxiii. 



