324 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



All the specimens are much battered — but all show an apical thick- 

 ening of the gelatinous substance, either as a circumscribed " top- 

 knot " or as a more gradual swelling. This was true likewise of the 

 eastern Pacific specimens, of those recorded by Browne and Fowler 

 (1906) from the Bay of Biscay (as " coeruleum "), and of the Japa- 

 nese series recently described by Maas (1909). But the specimens 

 from Trieste studied by Neppi and Stiasny (1913) had none. 



R. velatum was known to occur in the Malaysian region (Maas, 

 1905), and it is widely distributed over the tropical Pacific; therefore 

 it was to be expected in the Philippines. The only surprising thing 

 about the records is that it was taken at two stations only. 



Family HALICREASIDAE Fewkes, 1886. HALICREIDAE 

 Vanhoffen (1902) sens, em. 



Trachomedusae with eight very broad radial canals ; with numerous 

 tentacles of different sizes, but all structurally alike and arranged in 

 a single series; each tentacle divisible into a soft flexible proximal, 

 and a stiff spine- like distal region: with free sensory clubs; with 

 neither peduncle nor proboscis. 



The general structure of these remarkable Medusae is now well 

 known, thanks to Vanhoffen (1902), Maas (1905), Browne (1908), 

 and to the excellent series from the eastern Pacific (Bigelow, 1909a). 



Mayer (1910) classes the genera here included among the Trachy- 

 nemidae, uniting them with Rhopalonema and allied forms, as the 

 subfamily Rhopaloneminae, because of the absence of peduncle. But 

 they are separated from Rhopalonema, etc., by their very broad radial 

 canals; by the structure of the tentacles, which is extremely charac- 

 teristic ; by the large otocyst clubs ; and especially by the rudimentary, 

 flattened manubrium. On the other hand, they are a very homogene- 

 ous group among themselves. I need make no apology for retaining 

 them as a separate family, when in so doing I agree with every recent 

 student who has actually examined any of them. 



Genus HALICREAS Fewkes 1882. 



HALICREAS PAPILLOSUM, Vanhoffen. 



Halicreas papillosum Vanhoffen, 1902, p. 68, pi. 9, figs. 7, 8 ; pi. 11, fig. 30. — 

 Maas, 1905, p. 57, pi. 10, fig. 70; pi. 11, fig. 71.— Bigelow, 1909a, p. 138, 

 pi. 3, fig. 3 ; pi. 33, figs. 8, 9 ; pi. 34, figs. 1-3, 5, 8, 10, 11. 



Halicreas papillosum — material examined. 



