288 ORDER FLAGELLATA-PANTOSTOMATA. 



two or four macrospores within spheroidal cavities of the gelatinous zootheciuni 

 previously occupied by the parent zooids. 



Spongomonas uvella, Stein. Pl. XL Figs. 15 and 16. 



Animalcules ovate, nearly twice as long as broad, forming an erect, 

 lobulate zoocytium, which tapers posteriorly into a short, slender, and almost 

 stalk-like point of attachment ; expanding distally into a variable number 

 of closely associated ovate lobules, each of which is inhabited by a separate 

 zooid ; flagella rarely exceeding twice the length of the bodies, mostly less. 

 Length 1-2100", height of zoocytium 1-500". Hab. — Fresh water. 



The largest colony-stock of this species figured by Stein and here reproduced, 

 contains about a dozen zooids only. No indication is given of spore-production, 

 after the manner of the two preceding types. 



Spongomonas sacculus, S. K. Pl. XI. Figs. 17-23. 



Zoocytium granular, rust-brown colour, subglobose or sacculate, pendant, 

 many individual zooids crowded within each saccular diverticulum of the 

 common mass ; the social colony-stock produced forming in its entirety a 

 conspicuous object to the unaided vision ; animalcules elongate-ovate, twice 

 as long as broad ; flagella about twice the length of the bodies ; contractile 

 vesicle lateral ; endoplast ovate, central. Length of zooids 1-3250", of 

 adult saccular zoocytium 1-25" to ^". Hab. — Bog water. 



This species was obtained by the author in September 1879, in bog water col- 

 lected at Lustleigh Cleave, S. Devon, in company with Rhipidodcndnvi Huxleyi. As 

 first encountered it was passed over as mere flocculent inorganic debris adherent 

 to the sides of the glass receptacle, and it was only by the accidental inclusion 

 of a fragment with the examined specimens of the last-named type, that its presence 

 and true nature were elicited. Once recognized, its existence in corresponding or 

 even greater abundance than Rhipidodendroii became apparent, and data of interest 

 concerning its structural characteristics and rapidity of growth were placed on 

 record. In this last connection, more especially, it was found, by taking diurnal 

 measurements, that a colony-stock which on a given day presented in its total bulk 

 the size only of a grain of millet-seed, or a diameter of 1-25", might within three 

 days so increase in calibre as to form a subpyriform pendulous sac, equalling or 

 slightly exceeding the length of half an inch. From this point the zoocytium 

 usually became disintegrated, and, falling away piecemeal, liberated the contained 

 monads into the surrounding water under conditions favourable, no doubt, for the 

 establishment of new colonies. A delineation of the contours of such a colony-stock, 

 as observed at the commencement and termination of three consecutive days, is 

 reproduced at Pl. XI. Figs. 18 and 19. 



When examined with a high magnifying power, a conspicuous feature of the 

 zoocytium of this type, shared, however, not only by the remaining members of this 

 genus, but being in a less degree characteristic also of the more substantial zoo- 

 thecia and zoocytia of Rhipidodendroii, Phalansttrium, and apparently Cladoiiionas, 

 is manifested by the exceedingly regular distribution and even size of the granular 

 particles distributed through its substance, and which add so materially to its con- 

 sistence. In the present instance, these granular elements, taken sejjarately, are 

 of a roughly spheroidal shape, having a diameter of about one-tenth of the length of 

 the associated monads, or the i-3o,oooth of an inch, and exhibit by transmitted light a 

 pale amber hue. So densely are these minute particles packed together within the 

 transparent and mucilaginous element of the zoocytium, that they represent at 



