GENUS COD OS IG A. 335 



number of spore-like bodies, as shown at Fig. 27. It is not improbable that 

 previous to this encysting process, conjugation with other free-swimming animalcules 

 is effected ; but such a genetic union has not up to the present time been witnessed 

 by the author, but is reported by Stein. 



Biitschli, who has recently examined this form,* is disposed to maintain that 

 food is ingested outside the membranous collar, through vesicular extensions that 

 may be developed at any point close to its base. This interpretation, however, 

 together with the original separate mouth theory advanced by Professor Clark, 

 becomes quite untenable when set side by side with the evidence recently adduced 

 relative to the nature and function of the collar, and as explained at length in 

 the introductory notice of this group. Although normally only two spherical con- 

 tractile vesicles, as represented by Biitschli, are to be observed in the posterior 

 extremity of the body, as many as three are not unfrequently to be found, though, 

 as explained by Professor Clark, this is more usual in examples about to increase by 

 longitudinal fission. The systole and diastole of each of these vesicles, as observed 

 by the author, occupy a duration of 60'" ; Professor Clark, however, gives only half 

 this time. The adherent bacteria interpretation, now abandoned, but formerly 

 connected by the author with the echinate or amceboid state of this animalcule, is 

 adopted independently by Biitschli in the publication quoted. Stein likewise figures 

 an example in his recently issued volume, with a similar bacterial explanation, and 

 also an instance in which the genetic union of a smaller free-swimming zooid 

 with a solitary sedentary one is apparently in process of accomplishment. In 

 both of these last-named instances, reproduced at PI. IV. Figs. 9 and 10, it would 

 seem probable, however, that the types figured are referable to the solitary genus 

 Monosiga rather than to the colonially associated one now under consideration. 

 Attention may be especially directed to the remarkable similarity that subsists 

 between a luxuriant and subspheroidal colony-stock of Codosiga botrytis, as repro- 

 duced from Stein's work, at PI. IV. Fig 6, and the subspheroidal or rosette-shaped 

 gemmules, consisting of similar closely aggregated collared monads, developed by 

 the sponge Halisarca lobidaris, delineated at PI. IX. Fig. 20. The addition of a 

 pedicle is alone required in this latter instance to render the two monad aggregates 

 indistinguishable. 



Dr. Charles Robin has very recently t figured a supposed variety of Codosiga 

 botrytis in which the characteristic collar is replaced by four rigid cirrhate processes. 

 It is quite evident, however, that this presumed distinct variety represents merely 

 that modified condition common to all members of the Choano-Flagellata, and 

 specially referred to and illustrated in the description given of Salprngxca amphori- 

 diiiiii, in which, the collar being withdrawn, simple pseudopodic extensions take its 

 place. There can further be but little doubt that the form obtained from the 

 Victoria Docks, figured and described by the author of this treatise in the ' Monthly 

 Microscopical Journal' for May 1869, under the title oi Acineta socialis, and com- 

 pared at the time with the Epistylis bot?ytis of Ehrenberg, is identical with a similarly 

 modified condition of the present species. Polymorphic tentacle-like processes 

 approximating more closely to the pseudopodia of an ordinary Rhizopod than to 

 the characteristic appendages of a true Aci/iefa, were distinctly observed, and their 

 presence accepted as rendering the relegation of the type to the order of the 

 Suctoria entirely provisional. 



Codosiga umbellata, Tatem sp. Pl. IV. Figs. 1-5. 



Bodies gibbously ovate, rather over twice as long as broad, clustered in 

 groups of from four to eight individual zooids at the terminations of a rigid 

 tripartite, bi-tripartite, or occasionally quadripartite branching pedicle or 

 zoodendrium. Length of bodies 1-1250". Total length of branching pedicle 



* ' Zeitschrift fiir Wissenschafiliche Zoolojrie,' Bd. xxx., Heft 2, 1878. 

 t ' Journal de I'Anatomie et Physiologic,' Nov. and Dec. 1879. 



