244 



THAXTER. MONOGRAPH OF THE LABOULBENIACE.fC. 



immediately below the integument, the two branches diverging so that the individual cannot be detached 

 without breaking one or both of them. The male, however, develops merely the simple rhizoid, shown 

 in fig. 8, a slight swelling immediately below the integument serving to hold it with sufficient firmness. 



Dimeromvces coarctatus Thaxter. Plate XXVIII, Figs. 1-5 and 17. 

 Proc. Am. Acad. Arts and Sci. ,Vol. XXXVI , p. 410. March, 1901. 



Male Individual. Receptacle nearly hyaline, consisting of usually three superposed cells, the upper 

 separated by a dark-colored constriction from a short, simple, two- to three-celled hyaline or brownish 

 appendage. The antheridia usually two, seldom three, borne singly from the successive cells of the 

 receptacle, from which they are separated by a small basal cell; the venter having an external depression 

 and not abruptly distinguished from the stout curved neck. Receptacle 35^5 X 6-7 fi. Appendage 

 25-50 fi. Antheridia 18 X 5 p. 



Female Individual. Receptacle consisting of a large basal cell about twice as long as broad, bulging 

 so as to form a rounded base which pushes the small brownish-black foot to a lateral or sublateral posi- 

 tion; the remaining cells, usually eight or nine in number, separated by horizontal septa and superposed 

 in a simple series; the lower cells greatly flattened, those above somewhat less so, the series ending in a 

 somewhat abruptly narrower terminal cell, which is more than twice as long as broad, subcylindrical, 

 its extremity rounded symmetrically and bearing a short, simple, usually four-celled terminal brownish 

 appendage, which is distinguished by a constricted dark basal septum, and terminated by a somewhat 

 inflated lighter larger cell, which becomes characteristically disorganized on one side, so that the append- 

 age appears to end in a slender curved projection. The remaining cells of the receptacle producing single 

 appendages or perithecia, except the basal and sometimes a subbasal cell. The uppermost of these 

 secondary appendages arises from the inner side of the subcorneal subterminal cell of the receptacle, 

 occupying a position in the median line between the primary appendage and the base of the first perithe- 

 cium, and consists of a short subcorneal basal cell, from the narrow extremity of which the simple, several- 

 celled terminal portion is distinguished by a constricted dark septum; the remaining appendages laterally 

 divergent on opposite sides in such a way as to appear paired, usually three on each side, each consisting 

 of a rather long basal cell inflated along its upper side so as to appear more or less geniculate, concol- 

 orous with the receptacle, its narrower extremity suffused with dark brown, distinguished without con- 

 striction by a dark septum from the simple terminal portion, which is usually five-celled, more or less 

 strongly recurved, brown, its terminal cell becoming inflated and undergoing gelatinous degeneration 

 on the lower side, which causes it to appear split in two, the hook-like upper half of the cell alone per- 

 sisting in some individuals. Perithecia yellowish, distally brownish, one, rarely two, in number; the 

 first always arising from the cell immediately below that which bears the upper secondary appendage, 

 the second, when one is present, replacing one of the appendages lower down; consisting of a symmetri- 

 cally inflated venter, which tapers gradually downward, passing into the short stalk; a short neck rather 

 abruptly distinguished, deeper brown below, its tip inflated below four terminal projections, three or 

 two of which are in the form of rounded papilla? of unequal size, and one or two of which are pointed 

 and much more prominent. Spores 42 X 3.5 fx. Perithecium, including the stalk, which is continuous 

 with it, 125 X 20-35 /j.. Receptacle to base of primary appendage 50-75 /i. Secondary appendages 

 about 75 /i. Total length to tip of perithecium 150-180 ji. 



Densely crowded on the inferior surface of the abdomen or rarely on the legs of a small pale fly. 

 Ralum, New Pomerania. Berlin Museum, No. 1282. 



Abundant material of this species has been examined and although it grows on the soft inferior 

 abdominal integument of a similar host and in the same position, it shows no tendency to develop the 

 haustoria which are so characteristic of the preceding species. The two are very closely allied, neverthe- 

 less, the form and disposition of the appendages, which project something like the legs of a crustacean, 

 affording the most striking points of difference. The individuals usually occur crowded in large nura- 



