THAXTER. - 



MONOGRAPH OF THE LABOULBENIACK/E. 



203 



growing as it does appressed on 1 1 it* anal appendages of its host. Although I have examined many speci- 

 mens of Hyrockaria Prom the same locality, a pond occupying the highest point on Cutt's Island, as well 

 as from other loealities in North and South America, I have seen this species but once. 



CHITONOMYCES Peyritsch. 



The additions to this genus have not been very numerous since the publication of my monograph, 

 in part because no special effort has been made to obtain them, and in part for the reason that small 

 exotic Dytiscidse do not appear to be well represented in the collections examined. Moreover, after the 

 host has been mounted and has become well dusted, it is almost absolutely impossible to see the smaller 

 forms. The genus is no doubt a large one, and species are sure to be multiplied when the tropical forms 

 can be examined fresh or in alcohol. Nevertheless a few very characteristic forms are herewith illus- 

 trated, among which C. psiitacopsis and C. Bullardi are among the most singular yet discovered. A 

 special interest also attaches to C. Javanicus, since, with C. marginatus and C. melanurus, it represents 

 a small group of species, closely allied and evidently either derived from one another or from a common 

 source, and all growing in exactly the same position on the same (left) wing of species of Laccophilus. 



No attempt has been made since the publication of my Monograph to determine more exactly the 

 nature of the antheridium which, in most species, is so small that it can be detected only with the greatest 

 difficulty, placed as it is on the side of the individual next the perithecium and thus never visible in pro- 

 file. A careful study of the antheridia, in forms like C. rhyncostoma or C. paradoxus, in which they 

 appear to be unusually large, is much to be desired. The close relation of this genus to Limnaiomyces 

 in which the compound antheridia are evident, cannot be doubted. 



All the species added herewith afford further illustrations of the remarkable constancy with which 

 these plants occur in definite positions on the hosts, a condition which is to me quite inexplicable unless, 

 as previously suggested, it is brought about by automatic motions of the legs while the insects are in 

 coitu. This explanation, however, seems insufficient to account for the restriction of eight or nine species 

 on a single host to a corresponding number of definite positions. 



The two nearly related species, C. Aethiopicus and C. Oreetogyri should probably be removed from 

 this genus, although very closely related to it. It will be necessary to examine young conditions, however, 

 before this can be determined. With the exception of these two forms which occur on Gyrinidw, the 

 species of the genus are all found on small water beetles belonging to the Dytiscidse and Haliplidse. 



Chitonomyces Hydropori Thaxter. Plate XXXIV, figs. 28-29. 

 Proc. Am. Acad. Arts and Sci., Vol. XXXVII, p. 32. June, 1901. 



Receptacle nearly hyaline, the subbasal cell flattened, many times smaller than the basal cell, slightly 

 inflated and distinguished from the cells above and below by slight constrictions; the two cells above 

 subequal, the posterior somewdiat broader, and separated from the lower marginal cell of the distal por- 

 tion by an oblique curved septum, which overlaps its upper fourth; the subterminal marginal cell often 

 nearly as long as the lower, the narrow upper half, or more, of which it overlaps. The lower appendicu- 

 late cell rather small, the upper terminal one of the typical form, relatively rather long, distinguished by 

 a slight constriction, the appendage extending beyond the tip of the perithecium. Perithecium relatively 

 large, its upper half, or more, free, distally broader, the outer margin nearly straight with as light subter- 

 minal rounded elevation below the abruptly rounded projecting outer brownish lip-cells; the apex other- 

 wise flat, broad, bent outward so as to be slightly oblique, the inner margin below it bulging and curved 

 throughout. Spores 55 X 4 y. Perithecium 98-108 X 25 ft. Receptacle to base of perithecium 80 y, 

 to tip of terminal cell 150 y. Total length to tip of perithecium 185 ft. 



On the mid-elytron of Hydroporus modesfus Aube, Cape Neddock, Maine (Mr. Bullard); on Hy- 

 droporus sp., Daytona, Florida. 



This species is distinguished by the broad out-turned tip of its perithecium and the enlargement of 

 the cells immediately above the very small subbasal cell. The Florida specimens are slightly smaller 



