246 SERTTJLABIIDJE. 



is generally of a pellucid whiteness, and throws about its 

 stems and branches in the most graceful curves. 



There is some variation in the degree in which the free 

 portion of the calycle diverges; in some specimens it 

 bends abruptly outwards, in others it rather inclines up- 

 wards. The internodes also are more or less produced and 

 attenuated below, and are often much constricted at the 

 joint. The operculum of the calycle is placed a little 

 below the aperture, and shows distinctly through the deli- 

 cate walls, giving the appearance of a transverse fold or 

 crease. 



The gonothecse* in an early stage are in the form of an 

 inverted cone, traversed by eight longitudinal ridges that 

 terminate above in as many angular projections (Plate 

 XLVIII. fig. 1, c]. In the perfect state, the female capsule 

 encloses an oval marsupial chamber, formed by eight ra- 

 diating, chitiiious tubes, which originate at the summit of 

 the column bearing the ovarian sacs. The ova are trans- 

 ferred from these sacs successively into the chamber, and 

 there pass through the later stages of their development f. 

 Airman describes the male gonothecce as having only six 

 of the longitudinal ridges ; but in all that I have examined 

 there were eight, as in the female. There are generally 

 from four to six sperm-sacs in each, forming a row, which 

 extends to the very top of the cavity. 



The capsules are sometimes borne in continuous lines 

 along the upperside of the pinnse, springing from the base 

 of each pair of calycles. 



Hab. On other zoophytes (chiefly) and on shells ; gene- 



* " Large and peculiar vesicles, alike difficult to be described and repre- 

 sented, are borne by the Sertularia rosacca." Dali/ell. 



t Fide Prof. Allman's " Eeport on the Reproductive System in the Hy- 

 droida," Eeport Brit. Assoc. for 1863, pp. 372-3. 



Lieut. Thomas also has given a very accurate account of the structure of 

 the gonotheca, in the Supplement to Johnston's ' Zoophytes,' pp. 468-9. 



