322 



THAXTER. MONOGRAPH OF THE LABOULBENIACEvE. 



strongly inward, tapering slightly to the blunt unmodified tip. Spores 35 X 3 fi. Perithecia 60-90 X 

 18-28 {i, the stalk 90-100 X 20 p. Receptacle 30-40 X 18 fi. Appendages 150-200 p. 



On the thorax, prothorax and adjacent legs of StUicus angularis Lee, on the right side; Arlington, 

 Mass., June. 



Although vcrv different from the type of Stichomyces this species seems provisionally referable to no 

 other genus. It has been found only once in company with Corethromyces near the pond in the Arlington 

 Park, where its host occurred in great abundance concealed in piles of dry melon stems. It may be men- 

 tioned that what appears to be the same species as well as certain others nearly allied, were found by me 

 on species of Sfilicus near Buenos Aires; but these forms have not as yet been carefully examined. In 

 habit it resembles Rhadinomyces, but differs in having free antheridia. As above mentioned the generic- 

 reference must be regarded as merely provisional. 



RHIZOMYCES Thaxter. 



The two additional species of this genus herewith illustrated indicate that, although its appendage- 

 characters are well defined, the presence of a penetrating rhizoid, which occurs in the type and suggested 

 the generic name, is not of generic value; since in R. ctenophorus the plant is attached by the usual foot. 

 The same condition is seen in Dimcromyecs and in Ceraiomyces, which further illustrate the unimportant 

 nature of the rhizoidal character. The species thus far observed all occur on the very peculiar flies belong- 

 ing to the Diopsidse, all of which are characterized by the possession of stalked eyes. It is uncertain, how- 

 ever, whether all the infested specimens belong to the genus Diopsis, since these insects are largely unde- 

 termined in the collections examined. 



Rhizomyces ctenophorus Thaxter. 

 Further material of this species was found in the Berlin Museum on African species of Diopsis; 

 No. 852 from Usambara; No. 861 from Zanzibar, and No. 853 from Wangunga. Although the species 

 varies considerably in the length of its perithecial stalk-cell, and in the development of its appendage 

 which may be much shorter than in the specimen illustrated in my figure, the characters seem otherwise 

 quite constant. 



Rhizomyces gibbosus Thaxter. Plate LI I, figs. 22-23. 

 Proc. Am. Acad. Arts and Sci., Vol. XXXVI, p. 409. March, 1901. 

 General habit more or less sigmoid. Perithecium amber-brown, concolorous, with its relatively 

 large basal cells, from which it is hardly distinguished, asymmetrically inflated, bent, and tapering some- 

 what distally; a subterminal abruptly rounded enlargement, beyond which the short asymmetrical tip 

 is clearly distinguished, bearing a large two-celled outgrowth posteriorly, the lip-cells being otherwise 

 unmodified: stalk-cell hyaline, variably, sometimes greatly elongated, separated from the basal cells by 

 a more or less distinct constriction. Appendage nearly hyaline, except the small deep brown sterile basal 

 cell, the remaining cells, three to seven in number, bearing short one- to two-celled branches distally and 

 laterally on which the free flask-shaped antheridia are borne singly or several together. Receptacle 

 short and stout, the upper cell several times as large as the basal cell, which appears to penetrate the 

 host directly by means of a rhizoidal apparatus. Spores about 35 X 3 fi. Perithecium, including basal 

 cells, 85-108 X 30-36 p; the stalk 60-160 X 18-20 p. Appendage 65-110 p. Total length to tip of 

 perithecium 180-325 



On the upper surface near the tip of the abdomen of a species of Diopsis. Berlin Museum, No. 

 850. Tanga, Africa. 



This species is well distinguished from the allied R. ctenophorus by the peculiar conformation of its 

 perithecium, and by its comparatively simple appendage. That it possesses penetrating rhizoids is evident 

 from an examination of the types, but in all cases they were broken in removal. 



