GENUS EPISTYLIS. 705 



stouter, solid, and with very short secondary branches. According to Ehrenberg's 

 figures, this type appears to form but small colonies, six zooids only being included 

 in the one selected by him for illustration. No recent investigator would appear 

 so far to have made the acquaintanceship of this animalcule. The examples referred 

 to this type by Mr. H. E. Forrest in the 'Midland Naturalist' for April 1879, 

 undoubtedly represent the erect variety of Epistylis flavicans. 



Epistylis branchiopyla, Perty. PL. XXXIX. FIGS, i AND 2. 



Bodies shortly ovate or subspheroidal, nearly as broad as long, widest 

 centrally, tapering posteriorly, slightly constricted beneath the border 

 of the peristome ; ciliary disc slightly protrusible ; cuticular surface 

 smooth ; pedicle erect, slightly curved, finely striate longitudinally, 

 branching dichotomously but somewhat unevenly, one limb at each bifur- 

 cation, and continually on the same side, considerably exceeding the 

 opposite one in height ; endoplast band-like, transversely placed. Length 

 of bodies 1-360" to 1-280". 



HAB. Fresh water, on the larvae of Phryganida. 



The species according with the above diagnosis and delineated in the accompany- 

 ing plate, is referred by Stein with some doubt to the E. branchiopyla of Perty, which 

 is but imperfectly described and illustrated. In accordance with Perty's original 

 figure, the pedicle consists of a thick erect main trunk, from which diverge laterally 

 and at close alternate intervals a few short slender stalks bearing the subspheroidal 

 zooids, a group of three or four similarly stalked zooids crowning the summit of this 

 trunk. Should this interpretation be correct, Perty's species, as recognized by Stein, 

 differs in the formation of its pedicle from all ordinary representatives of the genus 

 Epistylis, and more nearly approaches that of Zoothamnium alternans. It is at the 

 same time possible that this aberrant formula represents the impression conveyed 

 to Perty by the irregular branching of the pedicle characteristic of Stein's examples, 

 the size of the animalcules and the nature of the associated host being in both 

 instances identical. It may be mentioned that the zooids as figured and described 

 by Perty, while subspheroidal, exhibit a somewhat different outline from that given 

 by Stein, the posterior region being usually the broadest and somewhat flattened, 

 while the peristome- border is contracted, and represents the narrowest region of 

 the body. 



Epistylis crassicollis, Stein. PL. XXXIX. FIG. 19. 



Bodies ovate, or shortly fusiform, tapering posteriorly, as also in a 

 less degree anteriorly, about twice as long as broad ; peristome-border 

 greatly thickened, its diameter less than that of the centre of the body ; 

 ciliary disc scarcely exsert ; cuticular surface smooth ; pedicle branching 

 dichotomously, and at an acute angle, the individual zooids being usually 

 brought near together on the same level ; both main stem and branches 

 smooth, or faintly wrinkled transversely, the latter straight and of uniform 

 thickness, equalling in length the supported zooids, frequently with a 

 conspicuous raised annulus at the point of bifurcation; endoplast band- 

 like, horseshoe-shaped. Length of bodies 1-240". 



HAB. Fresh water, attached to the limbs of various Entomostraca. 



The largest colonies of this species contain from twelve to twenty zooids, but 

 a less number is more abundant. In its general mode of growth it most closely 

 approaches Epistylis anastatica. 



VOL. II. R 



