278 Rev. T. Hincks on new Hydroida and 



branched. Hydrothecce very large, separated by a joint, tall, 

 erect, very slightly expanded below and towards the orifice 

 (of very much the same width throughout), distinctly ribbed 

 transversely ; orifice quadrate, with four denticles and an 

 operculum, the stem below the calycles more or less annulated 

 or marked with transverse rugse. Gonothecce produced. at the 

 base of the calycles, ovate, subpedicellate, covered with pro- 

 minent transverse ribs, with a neck-like termination above, 

 and on the summit four large and conspicuous spines. 



Grows in somewhat straggling bushy tufts, which attain a 

 height of about 2 inches. 



This species bears a general resemblance to the 8. gigantea 

 of Mereschkowsky, which occurs in the White Sea * ; but 

 the latter has an angularly bent stem, and is also described as 

 having the margins of the cells "always furnished with several 

 ledges (sometimes 8 or even 10) and an equal number of small 

 opercula, one above the other." This is made a distinctive 

 character, and is said to be always present in adult cells. 



In these particulars S. gigantea differs from 8. quadricor- 

 nuta ; and though it may be doubtful whether the ledges below 

 the margin should be accounted a character of much signifi- 

 cance, I hesitate to unite the two forms without further evidence 

 of their identity. Unfortunately M. Mereschkowsky did not 

 observe the capsule of his species. That of 8. quadricornuta 

 exhibits very marked peculiarities, and separates it from any 

 form with which I am acquainted. In its ribbed character it 

 agrees with that of 8. tricuspidata, but it is distinguished from 

 it by its coronal of spines. 



The ramification of the present species is irregular; the 

 shoots bifurcate near the base, and the secondary shoots divide 

 and subdivide freely. M. Mereschkowsky identifies his 

 S. gigantea with the S. polyzonias, var. gigantea, mihi f, and 

 is surprised that I should not have recognized in the latter a 

 distinct species. I have not access, at present, to my speci- 

 mens of the Greenland variety ; but if my figures of it (drawn 

 with the camera) are to be trusted, it is certainly different from 

 the S. gigantea, Mereschkowsky ; and while the latter is un- 

 doubtedly entitled to specific rank, I am still unable to find 

 any character to separate the former from polyzonias but its 

 size. Sars appears to have taken the same view. 



I venture, then, to think, with great respect for M. Meresch- 

 kowsky's opinion, that his 8. gigantea and my 8. polyzonias, 



* " Studies on the Hydroida," Ann. & Mag. Nat. Hist, for March and 

 April 1878. 



* " On Deep-water Hydroida from C4reenland " (" Iceland " wrongly 

 in the text), 'Annals,' ser. 4, xiii. p. 151, pi. vii. figs. 11, 12. 



