THAXTER. — ARGENTINE LABOULBENIALES. 19L 



On I I etc rot ho p,s iiov. sp., No. li)S7, LUivullol. 



This curious form is most clearly distinguished by tlie peculiar 

 conformation of the tip of the perithecium and its relatively large 

 receptacle and foot; but is included only provisionally in the present 

 genus owing to the fact that the antheridia are not distinguishable 

 in an\' of the specimens. The host has been determined as a new- 

 species by Dr. Bernhauer. 



Corethromyces rostratus nov. sp. 



Perithecium tinged with pale brownish, long, slender, erect and 

 straight, symmetrical; the basal cell-region distinct from the more or 

 less inflated basal ascigerous part; the mid-region sometimes rather 

 abruptly narrower and elongate ; the tip not distinguished, symmet- 

 rical; the apex narrow subsymmetrical, hyaline, abruptly papillate: 

 stalk-cell small, concolorous, rather broader than long. Receptacle 

 externally prominent below the insertion of the appendage, the basal 

 cell large, subtriangular, suffused with smoky brown, externally 

 opaque, its broad distal surface obliquely separated from the small 

 flattish subbasal cell. Appendage somewhat divergent, consisting 

 of five or six superposed cells; the basal nearly hyaline; those above 

 it more distinctly suffused, and each bearing a branch from its distal 

 inner angle; the branches once to several times divided, the subbasal 

 cell of the lowest branch, in conjunction with the bases of its two or 

 three branchlets, rather characteristically inflated; the ultimate 

 branchlets slender, hyaline, cylindrical, associated with usually single 

 (?) antheridia. Perithecia, above basal cells, 120-135X20-22 f^: 

 the stalk-cell 6X8m. Receptacle 55-58 /x. Spores 30X3 m- Append- 

 age 95-100X12-14 fj. its longest branches 155 fx. Total length to tip 

 of perithecium 200-230 ix. 



On various parts, usually the abdomen of Heterothops sp., Temperley, 

 No. 2000, Llavallol, Nos. 1985 and 1987. 



It seems difficult to obtain this species in very perfect condition, 

 and though I have examined material from a number of different 

 individuals, I have been unable, even in the younger specimens, to 

 determine the exact nature of the antheridia which appear to be 

 solitary near the bases of the lower branches of the appendage. It is 

 possible that I have mistaken short branches for these organs, and 

 in any case the reference of the form to Corethromyces as above emended 

 must be considered provisional. 



A well marked variety was also found having a hyaline obconical 



