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NOTES ON NOMENCLATURE X. 
Elizabeth G. Britton. 
Part 231 of Engler and Prantl Pflanzenfamilien was received on July 
16th, 1908; it includes pages 1009 and 1056 completing the Thuidieae and 
beginning the Hypnaceae. The genus Thuidium includes 28 species found 
in North America, separated into live subgenera, and Helodium (Sull.) 
Warnst. (Eladium Sull.) is maintained with three species. 
The Hypnaceae are divided into four subfamilies as follows; 1, Am- 
blystegieae ; 2, Hylocomieae ; 3, Stereodanteae ; 4, Plagiothecieae , only the first 
two are included in this part. The Amblystegieae are divided into ten gen- 
era, all occurring in North America ; these are Amblystegium with 19 species, 
Amblystegiella four species, Homomallium two species, Hygroainblys- 
tegium four species. Amblystegiuin Lescurii Sull. with its thickened rough 
margin is very properly transferred to the genus Sciaromium founded on 
three South American species in which this is characteristic. A rigid interpre- 
tation would pronounce Hygroamblystegium filicinum the type of C'ra- 
toneuron Sull. which includes five of our species, C. commutatum being only 
incidentally mentioned by Sullivant. Drepanocladus includes 17 species and 
is subdivided into seven sections ; Calliergon con tains seven and Acrocladium 
cuspidatum stands as our only species. Hygrohypnum has 16 species which 
have been familiar to us as Limnobium. Campy lium includes 18 species* 
but a careful revision of the genus would probably reduce this number. 
The Hylocomieae include a number of genera not found in North Amer- 
ica. Ctenidium is maintained with three of our species, C. molluscUm 
being figured. The generic name Microthamnium is retained in preference 
to Stereohypnum as used by Professor Fleischer and 'Mittenothamnium 
Hennings, a question which is open to discussion ; eighteen species are 
known to be tropical American, one only having been found in Florida. 
Parts 232-233 were received December 22d, 1908, containing pages 1057- 
1152, completing the Hylocomieae and including the Stereodonteae, Plagio- 
thecieae, Leucomiaceae, Sematophyllaceae , Rhegmatodontaceae and part of 
the Brachytheciaceae. Rhytidiopsis Broth, is described to include R. 
robust a (Hook.) of the western states, R. rugosum remaining in Rhytidium. 
Hylocomium is limited to four of our species. Perhaps the most surprising 
result of the subdivision of the Hypnaceae is that the genus Hypnum is 
reduced to one species, H. Schreberi and that the'citation is Dillenius Cata- 
logue Gissam p. 215, 1718. It would seem more correct to have cited it as 
Hypnum (Dill. L.) as the method of arriving at the^type has been by exclu- 
sion of all the Linnaean species that have been referred to other genera, 
leaving H. parietinum L. which raises the question why this specific name 
dating to 1753 should not have preference over H. Schreberi of 1787 espe- 
cially since the priority of the H. proliferum L. is recognized ! 
The Stereodonteae are divided into eight genera of which four are North 
American. Ptilium crista-castrensis is the only species in the first genus. 
Ectropothecium has seven of which E. caloosiense only, is known in Florida. 
Stereodon includes the “ proper Hypnums ” of Lesquereux & James’ Manual 
