24 HYDROIDA 



Tuhilaria^ and that its medusoid gonopliores, if they are rightly perceived, cannot develop into medusae 

 of the Hybocodon type. 



The only locality from which Tiibnlaria piilclicr is recorded with certainty, is the shore near 

 Reykjavik, Iceland, where it has been found only once. 



Tubularia indivisa Linne. 

 1758 Tubularia indivisa Linne, Systenia Naturae, Kd. 10, p. 803. 

 1899 — obliqua ^ T. indivisa Bonnevie, Norske Nordhavs-Expedition, p. 24. 



"Colonies, whose long dark browu-coloured hydrocanli are, in the lower part, twisted together. 

 The stems are covered with a vigorous perisarc, but show no rings nor wrinkles. No collar is formed 

 below the polyp. The polyp has a basal whorl of 20 to 30 tentacles up to 20 mn:. long; the distal 

 tentacles are up to 3 mm. long and densely crowded round the orifice in a whorl consisting of 

 several rows. 



The female gonopliores are eumedusoid with four rudimentary radial canals, one of which 

 (the shortest) is often slightly indicated even in the gouopliore fully developed. The gonophore 

 has, near the apex, a tentacle-like bulging, obliquely situated. The male gonophores are crypto- 

 medusoid and almost wholly globular, not oval. The gonophores are born upon up to 10 blasto- 

 styles, which attain a length of 10 mm. The actinula-larvae, when set free, wear filiform 

 tentacles". 



Material : 



"lugolf" St. 31, 66°35'N., 55^54' W.; depth 88 metres 1,6° C. (Davis's Straits). 



— St. 87, 65°o2'. N., 23°56'2W.; depth no metres (West-Iceland). 

 Greenland: Davis's Strait (without further data). 



— Egede's Minde ( — — — ). 



Iceland: Brede Bugt 65°i2' N., 23°28' W., depth 36 fathom.s. 



— Grindavik littoral. 



— Skagestrand depth 60 fathoms. 



— Vestmanno littoral. 



The Faroe Islands (witl)out further data). 



The North Sea: the West side of large Fishing bank 57°7' N., 2°4o' E., depth 37 fathoms. 



Swenander (1903) has pointed out ihaiTubzdaria obliqua Bonn e vie (1899) is based on female 

 individuals of Tubularia indivisa; thus in the very external characters of the gonophores this species 

 presents a peculiar sexual dimorphism, and inquiries into the conditions of the gonophores (Broch 

 1915) have made good that this sexual dimorphi.sm is a radical one, the female gonophores being 

 eumedusoid, the male ones on the contrary cryptomedusoid. — Tubularia indivisa is very easily con- 

 founded with the following .species, Tubularia rcgalis, particularly when only male individuals are in 

 hand for examination. In this case only the somewhat different shape of the gonophores makes it 

 possible to refer with certainty the individuals to one species or the other, the male gonophore of 



