2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



DITRICHACEAE (continuation) 

 CERATODON PURPUREUS (L.) Brid. 



Valle de Mexico : Desierto {Bro. Amable). 



CERATODON STENOCARPUS Bry. Eur. 

 Valle de Mexico: Desierto (Bro. Amable 1269). 



DICRANACEAE (continuation) 

 AONGSTROEMIA BRITTONIAE Ther., nom. nov. 



Aongstroemia pusilla Ther. Smithsonian Misc. Coll. 78" : 2. 1926. 



I name this species after Mrs. E. G. Britton, who had the kindness 

 to inform me that the name pusilla had already been used by Hampe. 



METZLERELLA LEPTOCARPA (Schimp.) Card. 



Valle de Mexico: Desierto (Bro. Amable 1254 in part). 



Mr. R. S. Williams has established (N. Amer. FI. 15: 153. 1913) 

 the synonymy of this species with Dicranodontiimi costaricense 

 (C. M.) R. S. Williams. I agree with him, but, following Brotherus' 

 example, I maintain the species in the genus Metzlerella. Thus the 

 name becomes Metzlerella costaricensis (C. M.) Broth. 



OREAS MEXICANA Ther., sp. nov. 



(Fig. I) 



Morelia: Cerro Azul (4793). 



Autoica, corticola, pusilla. Caulis vix 1-2 mm. altus. Folia sicca 

 crispula, humida valde patula, lanceolato-linearia, breviter et late acu- 

 minata, subobtusa, concava, canaliculata, marginibus planis, integris, 

 1.7-2.5 mm. longa, 0.25-0.35 mm. lata, costa basi 40^1, dorso laevi, ante 

 apicem evanescente, cellulis basilaribus hyalinis, rectangularibus, parie- 

 tibus tenuibus, sequentibus quadratis vel breviter hexagonis, saepe 

 transverse dilatatis, valde chlorophyllosis, tenuiter papillosis, parietibus 

 tenuibus, I0/aX6-8;u. Pedicellus sicca suberectus, tortellus, humida 

 superne cygnicollus, 1-2 mm. longus; capsula minuta, sicca suberecta, 

 cylindrica, valde sulcata, humida subglobosa ; peristomium simplex, 

 dentes (8) bigeminati, irregulares, nunc breves, e basi late triangulari 

 obtusi, 6-8-trabeculati, nunc elongati, 14-16-trabeculati (0.12 mm. 

 alti), longitudinaliter striati, sporae 18-24 /^ crassae. Caetera desunt 

 (capsulae deoperculatae). 



