26 



HYDROIDA 



below the polyp. The polyp 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 blastostylcs, which attain a 

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



Material: 



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



Tubularia rrgalis presents so many points of resemblance to Tnbnlaria iudivisa that the risk of 

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



200 m. 600m. tooom. 2000m. 



Text-fig. E. The occurence of Tithularia regalis in the Northern Atlantic. 



bnlaria regalis are larger than those of Tubularia iudivisa. But this is not the case in younger 

 individuals of Tubularia regalis., in wliich consequently the only certain distinguishing marks are pre- 

 sented Ijy the gonophores. The gonophores, indeed, are typical enough in the female individuals, but 

 arc not very conspicuous in the male ones, especially at earlier stages. The male gonophores of 7?^- 

 bularia regalis are oval, while those of Tubularia iudivisa are globular. It is evident from the diag- 

 nosis of the species, tiiat also Tubularia regalis jDresents a strong sexual dimorphism. The first who 

 got aware of this fact, was Swcuander (1903), who accordingly pointed out that the female had been 

 described as a different species Tubularia variabilis Bonne vie. 



Tubularia regalis is a fonn of true Arctic character, particularly occurring in the deeper 

 parts of the cold area. In the seas far towards the nortli it rises to shallower parts, and it is, for instance. 



