334 



ORDER CHOANO-FLAGELLATA. 



Codosiga botrytis, Ehr. sp. PL. II. FIGS. 22-29, and PL. IV. FIGS. 6-10. 



Bodies smooth and transparent, symmetrically ovate, more attenuate 

 posteriorly, about one and a half times as long as broad ; from two or three 

 to as many as twenty or more zooids, attached to the extremity of a 

 straight, slender, simple, rigid pedicle, whose height equals four or five times 

 the length of the body; their junction with this structure effected through 

 the medium of a slender flexible extension of the posterior region, which 

 frequently presents the aspect of a distinct secondary footstalk ; contractile 

 vesicles two or three in number, posteriorly located ; endoplast spherical, 

 situated in the median line in advance of the centre of the body. Length 

 of body, exclusive of the collar, 1-2500" to 1-2000", the collar when ex- 

 tended equalling the body in height. HAB. Fresh water, gregarious. 



It being now universally admitted that this species first described in an 

 intelligible and exhaustive form by the late Professor H. James-Clark, under the 

 name of Codosiga pulcherrima is identical with the Epistylis botrytis of Ehrenberg, 

 and Anthophysa solitaria of Bory and Fresenius, the specific title conferred upon it 

 by the earliest of these several investigators must necessarily take precedence of the 

 otherwise eminently suitable one proposed by the American authority. Among 

 the numerous specific forms of the genus Codosiga enumerated in this volume, 

 the present type represents the one most generally distributed. Since first meeting 

 with it in the neighbourhood of London in the year 1871, it has been obtained by 

 the author from innumerable stations throughout the country. Where once found, 

 it is, moreover, usually abundant, being eminently sociable in its habits, and not 

 unfrequently, as shown at PL II. Fig. 29, covering with a miniature forest-like 

 growth the thread-like filaments of various aquatic Confervae; the finely divided 

 leaves of Myriophyllum spicatum form likewise a favourable fulcrum of support for 

 this most elegant little species. At first sight it would appear that each separate 

 ovate zooid springs immediately from the rigid pedicle, but a closer examination 

 shows that each of these possesses a short, independent footstalk, which is, moreover, 

 flexible and endowed with the vitality of the body proper. This fact may be clearly 

 demonstrated by the observation of animalcules undergoing the process of longi- 

 tudinal fission, and at which times it will be seen that the short flexible footstalk 

 shares in the subdivision. As shown at Fig. 24, both the flagellum and the mem- 

 branous collar participate in the longitudinal subdivision of the zooid, the latter 

 structure during the process being conically contracted. 



During the author's earlier acquaintance with this animalcule examples were 

 frequently met with in which the entire surface of the body bristled with slender 

 rod-like projections, which were at first regarded as foreign bacterium-like organisms 

 accidentally entangled in the peripheral sarcode. Later on, however, it was deter- 

 mined that these structures were organically connected with the animalcule's body. 

 It was then thought that the individuals exhibiting this peculiarity belonged to a 

 separate species, and they were consequently figured and briefly described in the 

 ' Monthly Microscopical Journal' for December 1871, under the title of Codosiga 

 echinata. It has since been ascertained by the author that this supposed specific 

 variety is an amcebiform condition of C. botrytis previous to its passing into 

 an encysted state ; the short rod-like processes corresponding indeed with the 

 retractile pseudopodia temporarily developed under like circumstances by Salpingoeca 

 amphoridium, or other ordinary Flagellata. Sometimes, as shown at PI. II. Fig. 26, 

 these rod-like radiating pseudopodia are developed while the collar is fully expanded, 

 but more often both this structure and the flagellum are entirely withdrawn into 

 the substance of the body, which then presents the aspect delineated at Fig. 25. 

 Upon this amoeboid phase ensues an encysted condition in which the entire 

 cuticular surface becomes indurated, and the enclosed endosarc breaks up into a 



