436 



THAXTER. MONOGRAPH OF THE LABOULBENIACE^E. 



A second group of forms which, from the fact that they arc parasitic on species of a single aquatic 

 genus, Berosus, may be appropriately called Autoicomyces, is represented by the six described forms 

 above enumerated, and a seventh as yet unpublished. The members of this section differ from Cera- 

 tomyces in having a small and determinate number (seven and eight) of wall-cells in the perithel ia. 



The third group, of which the form previously described as C. rostratus may be taken as the type, I 

 have called Rhynchophoromyces from the monstrously developed necks which characterize the pcrithecia 

 of the species. The receptacle in this genus is many-celled and indeterminate, the perithecium distin- 

 guished into neck and venter, and later confluent with the base of the appendage, and at maturity its 

 axis is coincident with that of the receptacle. 



Lastly the two species formerly described as C. rhynchophorus and C. reflexus, together with two or 

 three others as yet unpublished, appears to differ very widely from all the other types, possessing a straight 

 erect axis of many superposed cells indeterminate in number, from which the perithecium, the wall-cells 

 of which are few in number and determinate, arises laterally. This type is further distinguished by the 

 production of what at least appear to be definitely differentiated antheridial cells, which are produced 

 much as in Ecteinomyces with which it has been provisionally associated above. To this genus from its 

 aquatic habit and parasitism on the Hydrophilida? I have given the name Hydrophilomyces. 



( )f these groups Autoicomyces corresponds in all respects to Ceratomyces, except in its determinate 

 perithecium, and is perhaps too closely allied to this genus. There can hardly be a difference of opinion, 

 however, as to the desirability of separating the others. 



Emended as above indicated, the genus Ceratomyces may be characterized as follows: 



Receptacle consisting of three superposed cells above the foot, surmounted by a pair of cells which 

 form the bases of the perithecium and of the appendage respectively. Cells of the perithecial wall- 

 rows indeterminate, both in different species and individuals: perithecium usually appendiculate below 

 the tip. Primary appendage consisting of a variably developed series of superposed cells, the lower 

 members of which may become longitudinally divided, and some or all of which may bear secondary 

 branched appendages arising from cells separated from their upper inner angles. 



This is a typically American genus, all the species of which, with the exception of the doubtful 

 C. terrestris found on Lathrobium, occur on species of the single hydrophilid genus Tropistcrnus and the 

 allied Pteurohomus in North and South America. The species vary very greatly in the number of mem- 

 bers which compose the rows of wall-cells in the pcrithecia, the extremes in this respect being well illus- 

 trated by C. procerus, in which there may be over sixty, and C. miniscuhis in which there are hardly more 

 than a dozen. This variability is not only striking as between species, but the number in different indi- 

 viduals of a given species is by no means constant and may be very variable. All the species with the 

 exception of the anomalous C. terrestris to which reference has been made above, and C. fill form is, are 

 characterized by the possession of a subterminal perithecial appendage variably developed. 



Ceratomyces filiformis Thaxter. 

 This species which usually occurs among the bristles along the margins of the elytra of its host near 

 the tip, is also found not infrequently between the terminal claws of the posterior leg. Material has been 

 examined from Eustis, Elorida and specimens have been obtained from Mexican Tropistcrni in the Paris 

 Museum, No. 50; and on Pleuroliomus obscurus Sharp from Duefia, Guatemala; Sharp Collection, No. 

 1185. It is somewhat anomalous and less well marked than any of the other species, seldom shows the 

 presence of branches on its appendage, produces very few spores and varies greatly in the length of its 

 perithecium and in the numbers of cells which compose it. 



Ceratomyces procerus Thaxter. Plate EXIX, fig. 6. 

 Proe. Am. Acad. Arts and Sci., Vol. XXXVII, p. 43. June. 1901. 

 Rather pale amber-brown. Perithecium very elongate, of nearly equal diameter throughout, the 

 wall-cells in each row more than sixty in number; the conformation at the tip similar to that in C. con- 



