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 

 vvo extremes, of the multitudinous changes of outline to which 

 this Diatom submits, imder 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 ot the greatest obstacles to the progress of 

 natural science, I forbear to increase their numbers. 



Plate I. fi^. 7. Side view of Cocconema lanceolatum 3. Fio- 8 S V of 

 C. lanceolatum y. *=' * "^ 



St/nedra funtinalis, n. sp. Frustules scattered ; S. V linear 

 lanceolate, m the smaller specimens elliptical lanceolate • 

 extremities produced subcapitate; nodule indefinite. Stri^ 

 2/ in -001". Length -0006" to -0014" Greatest hvP^Ath 

 of valve -00015" t? -0002". v.s. 



^igZf. '""'""- ^P'"'^ "'"' '^' ^"^"* S*^"^^^ ^t ^^S^^res de 



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



^'•Oof^"^;7:nm9f''S''^/^^^^ ^^°Sth of frustule 



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



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



•ooS'^^^^^^^^^^^ ^--"'e -ooir' to 



V«r P ni! ^/"P^S"^ near Cauterets, elevation 4930 feet 



Jqns f'.^P r n'' '^'y^'^""^ 2296 feet; Val d'Ossau, elevation 

 29Gb feet ; Cascade Gavarnie, elevation 6294 feet. ^^e^ation 



Both these varieties occur intermixed with the ordinary frus- 

 tules described m the ' Synopsis,^ and with frustules of O^^^ 

 don, all these appear to be forms of the same species thou4 

 the one described as O. hyemale in the ^ Synopsis^ is hi fa^the 

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

 normal condition of the mature frustule 



in PI 7T" rn ''''*°'*''^ '^^^^^^on of var. ^, which I have figured 

 m PI. I. fig. 10 « occurs m the Cambuscou gathering in tolerable 

 abundance This variety illustrates the tendency to a repet tion 

 of accidental deviations impressed by the self-div.ding act which 

 I have noticed m the Introduction to the Synopsis, vol ii ^ x^Hi 



