328 Transactions of the Society. 



fungi, as the Tuheracese. The same sequence is also to be met with 

 in some genera belonging to the Hepaticee. Throughout the fungi 

 the rule is that the largest and most elaborately ornamented spores are 

 met with in the morphologically lowest groups, and the same rule 

 holds good for the species constituting a genus. 



Externally the species included in the Trichiaceas frequently re- 

 semble each other closely, and, from what has already been said, it will be 

 seen that general form is of little value in the discrimination of species 

 as understood in the present work ; hence I have not attempted to give 

 synonyms dating further back than Rostafinski's monograph, unless 

 justified by the existence of type specimens ; but for the peace of mind 

 of those who consider synonyms as of far greater nnportance than a 

 knowledge of the organism treated of, I have added the synonyms 

 given by Eostafinski, but it must be clearly understood that they rest 

 entirely on the authority of the last-mentioned author, whose genius 

 in being able to give so many, and with such apparent certainty, I 

 admire. 



Key to the Genera. 

 I. Maters free. 



Trichia. — Elaters simple or branched, spirals well marked. 

 Oligonema. — Elaters simple or branched, spirals rudimentary. 



II. Elaters fixed hy one end to wall of sporangium, not combined into 



a net. 



Alwisia. — Free tips of elaters simple or slightly branched, spirals 

 rudimentary. 



Prototrichia. — Free tips of elaters much branched, spirals well 

 marked. 



III. Elaters combined in a net usually with free ends. 

 Hemiarcyria. — Spirals well marked, often furnished with spines. 



Trichia, Haller (emended). 



"Wall of sporangium single, dehiscing irregularly ; capillitium 

 consisting of free, simple or branched threads having the walls 

 furnished with raised bands arranged in a spiral ; spores globose, 

 epispore smooth or variously ornamented, yellow or orange, sometimes 

 tinged with red or brown. 



Trichia, Haller, Helv., iii. p. 114; Rost., Mon., p. 243'; Cooke, 

 Myx. Brit., p. 61 (in part) ; Sacc, Syll., v. 7, pt. i. p. 438 (in part). 



A genus marked by the presence of well-developed external ridges 

 arranged in a spiral manner on the perfectly free elaters or threads 

 of the capillitium. The elaters are in most species unbranched, cylin- 

 drical or fusiform, and more or less attenuated at the ends into a smooth 

 spine. In a few species the elaters are branched, the ends varying from 

 three to ten. The only other genus with free elaters is Oligonema, 

 but here the spirals are at best rudimentary, and the tips obtuse. 



