94 



HYDROIDA II 



one in the median line near the base. The internodia of the hydrocladia have each a hydrotheea and 

 three sarcothecae, a snpracalycine pair near the hydrotheea aperture and a median proximal of greatly 

 varying length. The proximal sarcotheca is tnbnlose, and has an open connection with the lumen of 

 the hydrotheea; in the outer parts of the hydrocladium, it forms a more acute angle with the branch 

 axis than nearer the stem; its free parts are in forma typica up to 2 / 3 the length of the hydrotheea, 

 in forma Billardi however, as a rule longer than the hydrotheea. The hydrotheea margin has an 

 abcauline tooth, and on either side, between this and the hydrocladium, three, or more rarelv four 

 teeth. One or two internodial ribs are seen at the wall of the hydrotheea; at times an intrathecal 

 rib may be indicated. 



The gouothecse are situate on a hydrocladium which has broad lateral blades converging to 

 a corbula; the basal pair of blades is as a rule free, and hangs out and downwards; there is a hydro- 

 theea between the corbula and the stem. The gonotheeae are pear-shaped. 



Material : 



"Thor", 35°57' N, 5 °3 5 ' W., depth 740 metres. 



The synonymy of the species has been dealt with in detail on a previous occasion (Broch 

 1912 p. 8) and notice has also been taken of the variations. Geographically, Aglaophenia tubulifera 

 is a southern species, only quite exceptionally passing beyond the limit of the boreal waters round 

 the British Isles; it belongs more especially to the middle and lower parts of the littoral region. 



Family series Sertulariina nov. 

 Family Sertulariidae. 



The hydrothecae are bilateral in structure and furnished with closing apparatus formed of from 

 one to four plates. The colonies form sympodia or monopodia with terminal growth point. The polyps 

 have a more or less pronounced abcauline and basal blind sack with a low, non-digestive endodermal 

 epithelium; they are therefore bilaterally symmetrical. 



Few families have been the subject of so much dispute as the Sertnlariidtr, both as regards 

 limitation and also in respect of division into genera. The best foundation is that given by Levin- 

 sen in his latest work (1913) where he comes to the same result as Stechow (1913). The latter 

 writer here separates off the Syiitlieciidcp as a distinct family comprising those forms which lack the 

 lid; but while Leviusen also discards this group and refers it to the family Lafoeidm, Stechow 

 considers the Syntheciidce as an independent family, most nearly related to the Sertulariid(r sens, 

 strict — a view in which we may fully concur, owing to the homogeneous organisation of the polyps. 

 This principle for division is not very fully dealt with by Leviusen, and in particular the special 

 organisation of the abcauline blind sack and its endodermal peculiarities seem altogether to have 

 escaped his attention. This is suggested, as already mentioned, by his reference to a blind sack in 

 Lictorella pinnata (G. O. Sars) which from a purely anatomical point of view is hardly tenable. Com- 



