STYLASTERIDAE (HYDROCORALS) FROM SOUTHERN SEAS 43 



cyclosystems are evidently larger, and their diameter may here (in complete systems) attain a length of 

 about i-i mm. 



The gastropore is fairly deep and so arched that the lower part of its longitudinal axis is almost 

 parallel to the axis of the stem or branch. The upper part of the pore is feebly narrower than the lower . 

 The lower apertures of the dactylopores are found as minute round pores just beneath the feeble ledge 

 limiting the 'basal chamber' from the narrower, funnel-shaped distal part of the gastropore. No 

 sphincter is developed between the two compartments. 



The dactylopores have large distal and small basal apertures. A great dactylotome, about half as 

 long as the wall of the outer compartment of the gastropore, connects the dactylopore distally with the 

 gastropore (see Fig. 9). 



Ampullae are not visible externally on the fragment. 



A small piece of the specimen was sacrificed for examination of the soft parts. 



The surface of the colony is equipped with numerous small nematophores which appear as round 

 spots. Under the microscope a mass of large stinging capsules is seen, larger and obviously different 

 from the small capsules of the dactylozooids. Fixation of the material, however, is not good enough 

 to allow of closer examination of the types of capsule. 



The polyps are of course contracted (Fig. 10). The gastrozooids are globular with no trace of tentacles. 

 The epithelium of the wall of the lower gastropore chamber can close sack-like over the contracted 

 zooid (Fig. 10, c.w.), and at the same time the large, finger-shaped dactylozooids are doubled down, 

 their tips in many cases reaching to the closed sack. The adnate basal part of the dactylozooid is 

 comparatively small, being only a little broader than the basal breadth of the zooid. 



The fragment is from a male colony. The ampullae are completely embedded although placed near 

 the surface of the stem and branches. They are furnished with a well-developed efferent duct (Fig. 11, 

 e.d.), which in most cases opens into the outer part of the cyclosystem funnel, a little outside (above) 

 the dactylozooids. The ducts may open anywhere on the surface of the colony. 



Owing to the scanty material only one series of rather thick sections in celloidin was examined. 

 Details of the gonophores can therefore not be given. The ampulla contains one large ' blastostyle ' 

 carrying a great number of small gonophores (Fig. 11); the apical gonophores, placed next to the 

 efferent duct of the ampulla, have ripe spermia, whereas the basal ones are as yet only quite rudimentary 

 buds. The production of gonophores evidently continues for some time, spent gonophores being 

 successively replaced from the basal part. 



The present specimen diverges strongly from C. tenuis and C. major, but is definitely more closely 

 related to C. dura (Hickson & England, 1908). However, the description and drawings of the last- 

 named species reveal differences, which do not indicate specific identity. Both species have numerous 

 small nematophores on the surface of the colony ; but in C. dura the authors say that the nematophores 

 have 'slightly raised lips', and such lips are wanting in the Discovery fragment. The surface of 

 C. dura is characterized as 'smooth' (in the drawing it seems punctuated), whereas the Discovery 

 specimen has an obviously and peculiarly vermiculated surface. 



In the cyclosystems we find that those in C. dura are ' irregularly distributed on all sides of the 

 branches and main stem', whereas the present colony has a naked posterior side and the cyclosystems 

 arranged in rather distinct rows laterally and anteriorly. Although the shape of the cyclosystems in 

 C. dura is characterized as ' irregular ', the drawings show that they are complete without any diastemma 

 in the dactylozooid circle. The drawings also indicate that the mouth of the cyclosystem in C. dura 

 projects a little over the surface of the coenosteum. These are differences which distinguish dura from 

 the Discovery specimen, which also has no horizontal septum between the upper and lower chambers 

 of the gastropore, the limit being only feebly emphasized by a rudimentary ledge, on the lower side 



