H. JAMES-CLARK ON THE AFFINITIES OF SPONGES. 313 



that genus, the body is not attached to the calyx by any visible means. It cannot be a 

 Dinobryon, since that, as Claparede has already shown, has but a single contractile vesicle, 

 and moreover it is situated near the anterior end of the body, and just behind a red eye- 

 spot. Dinobryon has a slightly notched, asymmetrical front ; in fact, it is a calyculated 

 Euglenian. The general tint of the body of Codonceca costata is a dingy yellow, whilst the 

 calyx (c) is colorless, and excessively transparent. The shape of the body is oblong, rounded 

 posteriorly, and slightly pointed in front, where the flagellum (fl) is attached. Its posterior 

 half nearly fills the basal third (c 2 ) of the calyx. 



The flagellum (fl) has not that rigid carriage which is so characteristic of that of Bicosoeea 

 (§§ 3 and 4) and Anthophjsa (§ 11), but is a truly vibratile organ. It is kept in an almost 

 constant state of rapid agitation, and projects at the same time far beyond the rim (c 1 ) of 

 the calyx. It is by no means easy to detect, even with a power of eight hundred diame- 

 ters, not only because it is seldom at rest, but on account of its excessive delicacy ; yet 

 when it does stop its vibrations, its character and proportions can be unequivocally demon- 

 strated under the proper circumstances of illumination and adjustment. It is about twice 

 as long as the body, and has a decided, although not rapid taper at its distal termination. 



The mouth remains yet to be discovered. There can be no doubt, however, that it is an 

 aperture of no very small extent, or at least that it is capable of considerable distension, 

 inasmuch as we find quite large angular particles within the body. That it is terminal 

 rather than lateral, is probable from tbe similar position of this organ in the not very dis- 

 tantly allied genus Codosiga (§ 6). 



The two contractile vesicles (cv, cv) are situated midway between the front and hind ends of 

 the body, and at two nearly opposite points. They are of moderate size, yet not so large 

 as those of Codosiga (§ 6), which they resemble, but exhibit a much feebler action than the 

 latter. 



The calyx (c, c, 1 <?), or carapace so called, has an ovate-campanulate outline, but is divided, 

 by a constriction, into two regions. One of these, the basal (c 2 ) or posterior third, is about 

 one half as wide as the remaining two thirds (c), and possesses an ovate-obconical form, 

 which tapers abruptly into the pedicel (pd). The anterior two thirds (c) arises from the 

 sharp constriction with a strong swell, or bulging, and then, narrowing a little, terminates 

 with a truncate aperture (c l ) ; so that on the wdiole this portion may be compared, in shape 

 and proportions, to a claretrglass. This region is peculiar moreover in being longitudinally 

 banded or sulcated by about twenty furrows, which terminate at the rim in as many notches, 

 that alternate with a like number of distinct scallops. Of these two regions the basal one 

 is quite distinct, although perfectly hyaline ; but the banded part is much fainter, and re- 

 quires a careful adjustment of the light in order to bring it out clearly. The pedicel (pd) is 

 moderately slender, colorless, at least as long as the calyx, and of a uniform thickness from 

 base to top. 



§ 6. Codosiga, nov. gen. 1 (C. pulciierrimus, nov. sp.) 

 (Plate IX., figs. 7-27.) 



This infusorian is as eminently a compound flagellifer as Anthophysa (§ 11) ; and although 

 not a heteronematous form, like the latter, it bears a very striking general resemblance to 



l kijjSuv, a bell ; aiyau, to be silent. 



MEMOIRS BOST. SOC. NAT. HIST. Vol. I. Pt. 3. 3 



