GENUS ANCYROMONAS. 247 



affected with these minute parasites occupied a restricted portion only of the pre- 

 mises on which they were first discovered. One point especially worthy of remark, 

 as recorded by Mr. Lewis, has reference to the position of the flagellum. If, as he 

 is inclined to maintain, this organ is produced from the posterior extremity, and 

 propels instead of draws the animalcule through the inhabited serum, we have 

 presented a structural and functional feature without parallel among the other 

 representatives of these Protozoa flagellata, the recognition of which would demand 

 the creation of a distinct generic and family group for the reception of these 

 singular organisms. The correspondence of these animalcules, this last-named 

 interpretation of the flagellum being correct, with the spermatozoa or male genetic 

 elements of ordinary Metazoic animals, is most remarkable, and not unnaturally 

 affords a foundation for the suggestion that further investigation may possibly 

 demonstrate their identity with the discharged spermatic elements of the minute 

 Nematodes, Micro-filariae, or other Metazoic endoparasitic forms known to flourish 

 amid the same surroundings. 



GENUS VII. ANCYROMONAS, S. K. 



(Greek, ancyra, anchor; monas.) 



Animalcules ovate or elongate, free-swimming or adherent at will ; 

 flagellum single, trailing, adhesive or anchorate at its distal extremity, 

 vibratile throughout the remainder of its length ; endoplast and contractile 

 vesicle conspicuous. 



The single type referred to this genus is of much interest, it combining in its 

 single trailing filament the functions of both the trailing and vibratile flagella of 

 such genera as Heteromita or Anisonema. It is further remarkable as corresponding 

 in its mature form with the earlier or larval condition of the representatives of these 

 two last-named generic types, in the former of which more especially (see Heteromita 

 rostrata and H. uncinatd) it has been demonstrated by Messrs. Dallihger and Drysdale 

 that the trailing or anchorate flagellum is the first to make its appearance, and 

 continues for a while the sole organ of locomotion. 



Ancyromonas sigmoides, S. K. PL. XIII. FIGS. 49-53. 



Body persistent in form, gibbously ovate or sigmoidal, about three times 

 as long as broad, the anterior extremity pointed and recurved ventrally, the 

 posterior one sometimes rounded, but more often shortly pointed and 

 slightly recurved in an opposite direction ; flagellum continuous with the 

 recurved anterior extremity, reflected backwards or ventrally, about twice 

 the length of the body, the distal extremity adhesive or anchorate, the 

 remaining portion vibratile or undulating ; endoplast spherical, subcentral ; 

 contractile vesicle situated close to the anterior extremity. Length 1-5000" 

 to 1-4000". 



HAB. Salt water, among decaying Fucus. Increasing by oblique fission 

 and by encystment and breaking up of the body into spores. 



This species was obtained at St. Heliers, Jersey, in September 1878, in vast quan- 

 tities, among a mucilaginous exudation from fronds of the seaweed Fucus siliquosa 

 that had been macerated in sea-water for the space of one week. As first seen 

 with a magnification of 800 diameters only, the author was inclined to anticipate 

 that the long, reflected and adherent flagellum was only one of two flagellate appen- 

 dages, and that another finer vibratile one was stationed at the anterior extremity 

 which would thus identify the animalcule with the typical representatives of the genus 



