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In the first division, the Operculce, the dehiscence is accomplished by the 

 formation of a circular slit at the summit of the ascus. The tension produced 

 when at maturity by the increase of their growth causes them to rupture circu- 

 larly at the summit, following the slit which is formed there, as I have previously 

 pointed out in certain Ascoboli ("Mem. sur les Ascobol^s," p. 11, pi. 10, fig. xxxi 

 and 8 and 9), throwing the operculum back by the sudden projection of the con- 

 tents of the ascus, leaving it generally a little elevated, with one space open or 

 sometimes almost closed. This operculum varies according to the form of the 

 extremity of the ascus. It is convex, when it is round, as in certain Humaria 

 and RyparoUus ; it is flattened, when the ascus is truncate, as in Aleuria; it is 

 mammular in the centre, when the extremity presents a similar character to 

 Ascoholus. 



When the ascus is larger, it often bends on each side, which causes it to 

 appear oval or triangular, as often occurs in Saccobolus. In almost all cases it 

 retains its round form very clearly when seen in front, and slighly raised when 

 seen in profile. The circular slip is almost always horizontal, but in a few rare 

 instances it is oblique, as in some species of Humaria. In one particular genus, 

 so well named by Mr. Renny, Ascosonus, it is perpendicular, and this form caused 

 me to doubt for a long time as to the true place this genus ought to occupy. If it 

 be considered as a slit, it will come in the Opcrcula, and I am now of this opinion, 

 in consequence of the great affinity existing between this genus and Ryparobius. 

 If it be considered as a simple rent of the apex of the ascus, which would not be 

 capable of softening, it will enter into the second section, as I had at first thought. 

 But I repeat, such cases form very^rare exceptions to the general rule. 



The group of Discomycetes, dehiscing by an operculum, presents some 

 characters which give an appearance of close relationship to all the species belong- 

 ing to it. Thus the sporidia of all those with which I am acquainted are simple ; 

 that is to say, they are without septa, sphserical, or more frequently oval, or 

 elliptical in shape, with their extremities rounded, rarely acuminate. They are 

 often warty and sometimes are reticulated. The consistence of the cups is almost 

 always waxy, less elastic than in the second division, except in some rare excep- 

 tions. The hairs, which are sometimes found on the exterior, are generally of a 

 different structure. The greater number of the species are found on the earth, on 

 dung, the soil of old trees, or rarely they are met with on sound dead wood, or on 

 the bark. This first division includes the Morels, the Hevellas, the Verpas, the 

 Pezizse of the sections, Aleuria, Humaria, many of the Lachnece, Ascoholus and 

 the greater part of the genera which are derived from this section. 



The second division, the Inopcrculce, is clearly separated from the first. 

 There is no longer a transverse or oblique slit at the extremity of the ascus ; the 

 extremity itself becomes softened in the centre at the moment of maturity, and 

 the tension which is then produced ruptures it, permitting the escape of the 

 sporidia with the liquid in which they exist. By the fact of this emission, the 

 margin of the opening becomes more or less turned like a collar, either entire or 



