26 



HVDROIDA 



below the poh-p. The pol^-p wears a basal whorl of 20—35 tentacles up to 40 mm. long; the distal 

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

 The female gonophores are eumedusoid with 3—6 external longitudinal ribs and as many 

 corresponding radial canals. The male gonophores are cryptomedusoid and oval, often with an attempt 

 to be pointed in the distal part. The gonophores are born upon up to 20 blastostyle.s, which attain a 

 length of 35 mm. The actinula larvae, when deliberated, wear filiform tentacles. 



Material : 



Between the Faroe Islands and the Shetlauds, depth 505 fathoms. 



Tulntlaria rcgalis presents so many points of resemblance to Tuhularia indivisa that the risk of 

 confounding the two species is very easily incurred. As a general rule, the full-grown polyps of Tu- 



200 m. boom. looo m. 2 ooo m. 



Text-fig. E. The occurence of Tiihularia jegalis in the Northern Athmtic. 



bitliirin rcgalis are larger than those of Tuhularia iudivisa. But this is not the case in yotinger 

 individuals of Tuhularia rcgalis^ in which consequently the only certain distinguishing marks are pre- 

 sented by the gonophores. The gonophores, indeed, are typical enough in the female indi\iduals, but 

 are not very conspicuous in the male ones, especially at earlier stages. The male gonophores of Tu- 

 hularia rcgalis are oval, while those of Tuhularia indivisa are globular. It is evident from the diag- 

 nosis of the .species, tliat also Tuhularia rcgalis presents a strong sexual dinujrphism. The first who 

 got aware of this fact, was Swenander (1903), who accordingly pointed out tliat tlie female had been 

 described as a different species Tuhularia variabilis Bonne vie. 



Tulntlaria rcgalis is a form of true Arctic character, particular!)' occiu'ring in the deeper 

 parts of the cold area. In the seas far towards the north it rises to shallower parts, and it i.s, for instance, 



