64 DISCOVERY REPORTS 



of the identities of Sars's two species because of their frequent association in these northern 

 waters. 



Agalma okenii Eschscholtz, 1825. 



Plethosoma cristalloides Lesson 1826; 1838. (For synonymy see Bigelow 191 lb.) 



Kawamura (1911a) studied specimens at Misaki in the winter. He observed, described and figured 

 specimens of what he considered to be two separate species, Agalma okenii Eschscholtz and Crystallomia 

 polygonata Dana. Specialists for the last forty years have thought that the two names were synonyms 

 of one and the same species, but Kawamura's criteria are clearly set out and illustrated on his plate 16. 

 Much research will be needed before his claim can be either supported or refuted. He considered 

 one of the characters of the smaller C. polygonata to be that in its nectophores there is only one vertical 

 ridge on the lateral facet, so that it has only two parts instead of the three found in Agalma okenii, 

 though reference to Dana's (1858) original figure shows that the nectophores had two vertical ridges. 



-C ped 



Text-fig. 25. Three views of a young nectophore of Agalma okenii from the Gulf of Aqaba, 'Manihine' St. 1, x 21. 



Only one ridge is developed on the lateral facet. 



Meanwhile, I am able to contribute towards what I believe to be the solution of the problem of the 

 existence of two types of nectophore associated with okenii type bracts, the two differing only in the 

 number of the longitudinal ridges on the lateral facets. The solution is that Kawamura's smaller 

 Crystallomia polygonata is a young stage of Agalma okenii. A long search through accumulated material 

 of A. okenii at last revealed the presence of two young specimens of A. okenii each about 1-5 cm. in 

 length having only two functional gastrozooids. A few larval type bracts were still attached, and the 

 budding nectophores all possessed two longitudinal ridges on the lateral facets. But each specimen 

 was associated with one or two nectophores, 8 mm. in diameter, that possessed only one longitudinal 

 ridge. I tentatively suggest, therefore, that the earliest nectophores, like the larval bracts, may have 

 only one ridge whilst the subsequently budded bracts and nectophores have more. The critical speci- 

 mens upon which this view is based are : 



'Terra Nova', 1910-13: 



Station 32. A series of nine young specimens taken in the tropical Atlantic south of the Cape Verde 

 Islands. The seven youngest specimens possess nectophores and buds of the 1 -ridge type. The two 

 elder ones possess nectophore buds of the adult (2-ridge) type. 



Station 63. Two young specimens taken a little further south than the last. One of them had still 

 attached to it a nectophore of the juvenile (1 -ridge) type, and was associated with detached nectophores 

 of the same (1 -ridge) type. In the catch also were pieces of a larger specimen and detached necto- 

 phores of the adult (2-ridge) type. 



