HYDKOIDA. BALE. 25 



shaped lip, which in the other forms rises out of a basin-like 

 concavity formed by the topmost aunulation, is here prominently 

 borne on the convex summit of the gonangium, which rises clear 

 above the annulation. 



For comparison with the foregoing I add descriptions of the 

 other two closely allied species which I possess, 8. johnstoni 

 and 8. pygmcea. 



S. johnstoni, New Zealand (PI, II., fig 10). — This specimen 

 is pinnate, similar in habit to the smaller varieties of 8. divaricata 

 and with the internodes, at least on the pinna?, bearing single 

 hydrotheea?. The latter are sub-conical, adnate a little more 

 than half their height, and directed a little towards the front. 

 They are smaller than those of any of the varieties of S. divaricata, 

 being about '27 mm. in length by '16 in diameter. In the other 

 characters of the trophosome I find nothing to distinguish the 

 species from S. divaricata. The gonangia, however, differ from 

 those of that species in being smaller and of narrower proportions, 

 and in having the annular ridges closer, more numerous, and less 

 prominent. Their length is from about 1*04 to Til mm., their 

 diameter from '47 to '52, and the annulations number twelve or 

 thirteen. The apei'ture is about '089 in width, and the neck is 

 tubular and rather thick, and in its position distinctly eccentric. 



^ fif. pygmcea (PI. II., fig. 11).— This is distinguished from 

 8. johnstoni primarily by the simple habit. The length of the 

 internodes is slightly less,— about -27 as against '31, — but their 

 angular form and the narrow, very oblique, and strongly twisted 

 joints are more distinctive. The hydrothecaa average about '27 

 by '16 mm., are less conical than those of 8. johnstoni, and are 

 mostly in the same plane. The gonangia are about as wide as 

 those of 8. johnstoni, but considerably shorter, their length being 

 from about "74 to '81 mm., and their annulations number about 

 eleven, In their general appearance they resemble those of 

 8. divaricata more than those of 8. johnstoni, owing to the form 

 and prominence of the annulations, which are especially 

 prominent towards the summit. The top one has the perisarc 

 much thickened, forming a deep cylindrical basin, from the 

 bottom of which rises the tubular neck, nearly filling it up. The 

 neck is similar to that of S. johnstoni, but owing to the depth of 

 the concavity in which it is situated it rises above the aunulation 

 only slightly, or not at all. The gonangia are not closely 

 appressed to the hydrocaulus, as in the allied species, consequently 

 instead of most of the adcauline side being smooth, the annu- 

 lations completely surround the gonangium, except for a short 

 distance above the base. The aperture is central. 



