66 DISCOVERY REPORTS 



with all doubtful synonyms. The five species are: triloba Haeckel, martagon Haeckel, laevis H. B. 

 Bigelow, clara R. P. Bigelow, and rubiginosa Kolliker, which is transferred from the genus Cunina. 

 Beside these only two species, 'Polycolpa ' forskali Haeckel and Pegantha magnifica Haeckel, may 

 possibly be valid species, providing the descriptions are correct, and if so the genus Pegantha 

 comprises altogether seven species. 



The following forms, which were referred to Pegantha by Mayer (1910), are unrecognizable: 

 Foveolia diadema Peron & Lesueur 1809 {Polyxenia diadetna Haeckel), tropical Atlantic; Aequorea 

 punctata Quoy & Gaimard 1824 {Solmaris punctatus Haeckel), Hawaii Islands; Polyxenia cyanostylis 

 Eschscholtz 1829 and Haeckel 1879, Atlantic Ocean; Polyxenia cyanolina Haeckel, Indian Ocean; 

 Solmoneta aureola Haeckel, Red Sea; Solmaris godefroyi Haeckel, Samoa Islands; Solmaris weberi 

 Haeckel, tropical Pacific. 



Aequorea cyanogramma Quoy & Gaimard 1824 {Polyxenia cyanogramma Haeckel) must likewise 

 be abandoned, though attempts have been made to revive it (Vanhoflten 1908, Ranson 1949). 



Medusa mollicina Forskal 1775 (Mediterranean), Pegasia dodecagona Peron & Lesueur 1809 

 (South Atlantic), and Polycolpa zonaria Haeckel 1879 (Mediterranean) may possibly be identical with 

 Pegantha martagon Haeckel as suggested by Bigelow (19 18), but it seems very doubtful. 



Pegantha biloba Haeckel (Sandwich Islands), P. quadriloba Haeckel (tropical Atlantic), P. pantheon 

 Haeckel (Philippine Islands), and Pegasia sieboldii Haeckel (tropical Atlantic) are probably identical 

 with P. triloba Haeckel. Pegantha dactyletra Maas 1893 (central Atlantic) is suggested by Bigelow 

 (191 8) as possibly identical with P. laevis; it rather seems to me to belong to P. triloba. 



Solmoneta liinulata Haeckel (Canary Islands) is a doubtful synonym of Pegantha clara R. P. 

 Bigelow, but too doubtful for a safe identification. 



The description of Solmaris sp. Browne 191 6 (Chagos Archipelago), which is designated by Bigelow 

 (19 18) as 'a typical Polycolpa', was based on young stages which may have belonged to some species 

 of Pegantha. 



Undoubted synonyms are: Pegantha simplex Bigelow 1904 {= P- martagon), Solmaris insculpta 

 Mayer 1906 {= P. triloba), and Pegantha smaragdina H. B. Bigelow 1909 {= P. clara R. P. Bigelow 

 1909). 



My studies of the numerous specimens of Pegantha in the Discovery collections and additional 

 observations of some fairly well-preserved specimens from the 'Atlantide' Expedition, off the west 

 coast of Africa, have led me to the following conclusions as to the structural features which may 

 serve as characteristics for identification of the species. 



Umbrella. It may be of specific importance whether the umbrella is highly vaulted or more or less 

 flattened, if the preservation is tolerably good, but frequently the shape cannot be relied on. In 

 P. triloba the sculpture of the exumbrella is characteristic, and the gelatinous substance is particularly 

 rigid. In species with a predominantly smooth surface, if the otoporpae seem to be deposited on 

 elevated ridges, it is merely due to casual contraction. 



Shape of the marginal lappets. It may be of importance whether the lappets are long or short in 

 proportion to their width. The relation between length and width varies according to the state of 

 contraction and preservation, but in extreme cases it may be a reliable character. The same applies 

 to the outline whether pointed, rectangular, rounded, or pentagonal, etc. 



The GONADS, which, of course, are undeveloped in young specimens, may sometimes have a charac- 

 teristic structure (especially in P. triloba) ; but their appearance is not merely dependent on the degree 

 of development, I have also found that a strong contraction in a circular direction may produce 

 foldings which are absent when the umbrella is flatly dilated. 



The NUMBER OF TENTACLES AND LAPPETS is an important specific character, though it is somewhat 



