196 Papers from the Department of Marine Biology. 



Genus LOBONEMA Mayer, 1910; sensu Light, 1914. 



Lobonema, MAYER, 1910, Medusae of the World, vol. 3, p. 688. LIGHT, 1914, Philippine Journ. of 

 Science, vol. 9, p. 216. 



GENERIC CHARACTERS. 



Rhizostomata triptera in which the marginal lappets are greatly extended, 

 tapering to pointed ends. These lappets are non-contractile and lack muscles. 

 Mouth-arms with numerous filaments. Mouth-arm membranes perforated 

 by window-like openings. 8 to 16 rhopalia and twice as many radial-canals, 

 and a ring-canal which gives off anastomosing vessels on both its inner and 

 outer sides. The inner network does not connect with the stomach. All of 

 the radial-canals extend beyond the ring-canal. The subumbrella exhibits a 

 well-developed system of ring-muscles. There are numerous, prominent, 

 tapering papillae upon the exumbrella. There is a sensory pit on the exum- 

 brella side above each rhopalium, and the floor of the pit exhibits radiating, 

 dendritic furrows. 



Lobonema smithii, the first-known species and type of the genus, was ob- 

 tained by the Albatross in Manila Bay, Philippine Islands, late in April 1908, 

 and described in Mayer's "Medusae of the World" (vol. 3, p. 689, figs. 417, 

 418). It is named in honor of Dr. Hugh M. Smith, Commissioner of Fisheries 

 of the United States. Another species from Palawan was described by Light 

 (1914, Philippine Journal of Science, vol. 9, p. 217, figs. 7-9) under the name 

 Lobonema mayeri. 



Lobonema smithii has only 8 marginal sense-organs, and the subumbrella 

 ring muscles are entire; while in L. mayeri there are 12 to 16 marginal sense- 

 organs and the circular muscles are completely interrupted in the ocular radii. 

 Light, who studied the medusas in life, states that the colors of Lobonema 

 mayeri are an exquisite scheme of purple, violet, and rose-pink. The gonads 

 are as a rule pink, the general color is violet, and the fringe of tapering 

 marginal lappets purple. Dr. Light tells me that in Lobonema smithii these 

 colors are not so brilliant and the bell of the medusa may be white. Light 

 finds that the sting of this medusa is not very severe and that the cases of 

 poisoning reported by Old were probably due to Dactylometra and not to 

 Lobonema. 



Light describes Lobonemoides gracilis, an immature medusa which may 

 possibly be a young stage of Lobonema mayeri. The marginal lappets are 

 pointed but are not very long, and there are no window-like openings in the 

 mouth-arm membranes. 



Genus THYSANOSTOMA L. Agassiz, 1862. 



Thysanostoma, AGASSIZ., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 153. 



GENERIC CHARACTERS. 



Rhizostomata lor if era having mouth-arms bearing 3 rows of frilled mouths 

 from base to lower end, without a terminal club. Among characters of minor 

 importance, the 4 interradial, subgenital ostia are wider than the perradial 

 columns between them. There are 8 rhopalar canals and a ring-canal which 

 gives off a network of vessels on both its inner and outer sides. This network 

 connects with all the radial-canals and also at numerous points with the 

 central stomach. The well-developed circular muscles are only partially 

 interrupted in the 8 principal radii. There is a small, shallow, exumbrella pit 

 above each sense-organ, and there are no furrows in the floor of the pit. The 

 only difference between this genus and the closely allied Lorifera is that the 

 frilled mouths are developed even to the tips of the lower ends of the mouth- 

 arm and there is no terminal club, whereas Lorifera has a naked terminal club. 



