I»I 



Fam. 8. TORTULACEiE. 



Plants generally rooting only at base, csespitant or pulvinate, 

 dichotoinous and fastigiate branched. Leaves ovate, lanceolate or 

 spathulate, soft, areolation above hexagono-quadrate and rounded, 

 usually highly chlorophyllose and papillose, at base larger, hexagono- 

 rectangular, hyaline. Calyptra cucullate, rarely mitrseform or lobed ; 

 caps, erect, oval, oblong or subcylindric, cleistocarpous, gymnostomous 

 or peristomate, teeth i6, on a more or less elongated tubular basal 

 membrane, lanceolate, or irregularly perforated, or cleft to base into 33 

 lineal or filiform legs ; strongly papillose, straight, oblique or contorted; 

 spores large and granulose or small and smooth. Inhabiting the ground, 

 walls, rocks and tree-trunks ; much more prevalent in the lowlands 

 than on mountains. 



This widely distributed family, so rich in species — for it includes pro- 

 bably not less than 800 — is a most difficult one to deal with, and has taxed 

 the ingenuity of every bryologist to arrange the species in well-defined genera. 

 The variations in habit, colour and leaf-structure afford more stable ground 

 for generic characters than the peristome, and this was first advocated by Mr. 

 Mitten in his, Musci India Or. (1859), but there has been an indisposition to 

 break up the great genus Tortula, resting solely on the twisted peristome, but 

 combined with a variable structure of leaves, and still stronger was the objection 

 to admit gymnostomous species as congeners with peristomate ones, although 

 no mosses more clearly exhibit the weakness of this distinction than some of 

 the old Gymmstomums now referred to Potfia, and the genus A nacalyp/ a. Lind- 

 berg in his Musci Scandinavia has fully carried out the modern views, and I 

 can only advise all bryologists to study the plants themselves under this 

 newer aspect, feeling assured that they will soon appreciate the soundness of 

 a natural classification. 



Mitten and Lindberg unite Pottia with Torhda, and no doubt correctly, 

 if we take a wide view of the genus, but as the Potlias have a certain distinc- 

 tive habit, and when the peristome is present the teeth have usually a flat 

 form, I have retained the genus, rather perhaps from the point of convenience, 

 as every one must see that Pottia ptisilla and Tortula lamellata ongkii to be 

 congeneric. 



We shall perhaps get the truest conception of the genera if we regard 

 each as the centre of a group of species, among which are phascoid, gymnos- 

 tomous and peristomate forms, and radiating in various directions towards 

 each other; e.g., Tortula ruralis and Encalypta streptocarpa have a strong point 

 of affinity in the verruciform papilla of their leaves. The form of the papillas 

 deserves notice, and they have not perhaps had sufficient attention directed 



