476 GENERAL HISTORY OF THE INFUSORIA. 



This affinity is particularly marked in the genus Stephanoceros on the part 

 of the Eotifera, and in that of Bowerhanhia on the side of the Bryozoa. 

 The members of the latter genus live in an elongated tubular case, and have 

 themselves an elongated, rather club-shaped figure. The case is transparent ; 

 its upper portion is soft, so that it can close over the animal when retracted. 

 The head of the Bryozoon is armed with several long processes or tentacles 

 similar to those of Stephanoceros, which are clothed with cilia and spines ; 

 and the margin of the head itself is also ciliated. This whole armature is 

 retractile. Muscles are distinguishable, mo\ing the several parts. The di- 

 gestive sj^stem comprehends a mouth, oesophagus, gizzard, stomach, a gastric 

 tube or pylorus, and an intestine, lined with cilia, returning upwards, so that 

 the anus opens near the mouth. The lining membrane of the gizzard is 

 moreover furnished ^dth many horny teeth, seated on oval muscular bulbs, 

 which, according to Mr. Gosse (see p. 473), ^'approach and recede in their action 

 on food, and seem to represent the quadiiglobular masses of Limnias and Ro- 

 tifer fui'ther degenerated." The Bryozoa as a class are reproduced by three 

 modes: 1. by ova; 2. by ciliated gemmules; and 3. by budding (gemma- 

 tion) from the common stem or polypidom where they grow. The second 

 mode is not met with in BowerbanMci, but only in species having fleshy or 

 gelatinous polyparies (e. g. Halodacti/lus), where the ciliated gemmules occiu' 

 in sacs, which appear as whitish points imbedded in the general mass. Is there, 

 we may ask, any analogy between these and the winter ova of Eotifera, which 

 are in some cases ciliated or haiiy ? The ovary producing the ordinary ova 

 is placed close above the stomach ; and contiguous to it is the testis, filled with 

 spermatozoa. The ova when ripe escape into the general cavity of the body, 

 • where they are surrounded and impregnated by the spermatozoa ; and after 

 several have accumulated about the base of the tentacles, they are at length 

 discharged through the anus. The ova are remarkable from their irregularity 

 of shape. The embryo escapes as a free being, not unlike some ciliated Pro- 

 tozoon, but by-and-by it fixes itself, produces its pedicle, and assumes the 

 form of its parent. 



On comparing this description of Bowerhanhia with that of Stephanoceros, 

 the points of similarity between the two are veiy many and striking. The 

 points in which BowerbanJcia chiefly differ are — 1. its character as a member 

 of a compound mass or polypary from which it may itself have grown as a 

 bud, whilst reproduction by gemmation is unknown among Eotifera ; 2. the 

 position of the ovary above the stomach, in close proximity, with an evident 

 testis ; 3. the apparent absence of an oviduct, and the consequent escape of 

 the ovum, followed by its fertilization, mthin the general cavity of the body ; 

 4. the imperfect development of a maxillary apparatus ; 5. the absence of a 

 water- vascular system ; 6. the greater length and stiffness and more slender 

 figure of the tentacles or arm-like processes of the head ; and 7. the different 

 disposition of the cilia upon them — for these in Stej^hanoceros are arranged 

 in little bunches or whorls at short distances from each other. 



But several of these distinctive particulars lose much of their force from 

 other comparisons and considerations. Thus the absence of an oviduct is 

 admitted as an occasional event in Eotifera ; and the escape of the embiyos 

 into the general cavity of the body has been stated by many observers to 

 occur in Stephanoceros ; Leydig, however, denies this ; yet the birth of the 

 young in Philodina and their active life mthin the body of the parent may . 

 present the analogy in request. It cannot be affirmed with certainty that 

 BoiuerbauMa is unlike Stephanoceros in ha\dng a testis #n company with the 

 ovary ; for no male Stephanoceros has yet been found, and some doubtful 

 structures have been by some assumed to represent the testicle. To cite yet 



