2&2 Dr Hooker and Dr Greville on the Genut HctJccria 



H. uncinata. Of these species, the authors of the Muscologies 

 Britannica, perhaps too hastily, considered that the seven 

 last should be rejected, as not well according with it, either 

 in their essential character or natural habit. We have here, 

 however, been induced to receive into the genus, Hookeria Jili- 

 culiformis, tamariscina and rotulata,* which, however va- 

 rying in habit, as they certainly do, from the type of the ge- 

 nus, agree with it, nevertheless, in the structure of their peri- 

 stomes, and we believe, (but we cannot speak with certainty,) 

 also in the form of the calyptra. We have indeed seen some 

 specimens of rotulata, where the calyptra appeared fully 

 formed, and was quite entire; whilst in others, even while re- 

 maining upon the capsule, we have observed it to be split on 

 one side. Still, from the general form of this part, which 

 may be considered as campanulate, we are inclined to think 

 that its splitting is an accidental circumstance, similar to 

 what we have seen, and what Schwaegrichen has figured, in 

 Trichostomumfunale, and which may perhaps be caused by 

 the sudden curvature of the seta, where it is embraced by the 

 base of the calyptra. Still we must allow that the union of 

 these species with Hookeria lacens, acutifolia, cristata and 

 quadrifaria, does in some measure destroy the natural habit 

 of the genus. But this we can safely affirm, that the more 

 we investigate the structure and character of the mosses, the 

 more we are satisfied that the nature of the peristome will not 

 afford characters for their natural distribution. What plants, 

 for example, can be more similar in habit than Cynontodium 

 cernuum of Hedwig, Leptostomum inclinansoi Brown, (Gym- 

 nostomum of Hooker) Ptychostomum compactum of Hornchuch, 

 and Bryum turblnatum ? So much alike are they indeed, 

 that with the eye, unassisted by the microscope, they are 

 scarcely to be distinguished from one another; yet in their 

 peristomes, and in them only, they are so widely different, that 

 according to the present ideas of the arrangement of mosses, 



• The Smithian Hookeria; which we think should be removed from that genus, 

 are the species last mentioned by that learned author; viz. Arbuscitla, jlexilis, and 

 uncinata. The two former are figured in the Musci Exotici as Hypna, and in the 

 cylindrical stems and general habit they certainly depart from the genus Hookeria ; 

 at the same time we must remark, that we have not, neither has Smith, had the 

 opportunity of seeing the calyptra. H. uncinata has altogether so much the habit 

 of Hypmtm aipressiforme, that till the discovery of its calyptra shall ascertain its 

 true genus, we should prefer placing it among the Hypna. 



