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MEDUSAE OF THE WORLD. 



Genus Parumbrosa Kishinouye, 1910. 

 Parumbrosa, KISHINOUYE, 1910, Journ. College of Sci., Univ. Tokyo, vol. 27, art. 9, p. 19. 



The type species is Parumbrosa polylobata Kishinouye from Toyama Bay, Japan. 



GENERIC CHARACTERS. 



Ulmaridae similar to the genus Discomedusa, but with 64 marginal lappets instead of 32. 

 This genus is evidently derived from Discomedusa by the bifurcation of its marginal lappets. 



Parumbrosa polylobata Kishinouye. 



Parumbrosa polylobata, KISHINOUYE, 1910, Journ. College of Sci., Univ. Tokyo, vol. 27, art. 9, p. 19, plate 4, figs. 20-23. 



Bell 160 mm. in diameter, flat, about 4 times as wide as high. Gelatinous substance 

 of delicate consistency. Exumbrella finely and uniformly graduated. 64 narrow, lanceolate, 

 pointed marginal lappets. 6 velar lobes between every 2 divergent ocular lobes. The velar 

 lobes are 3 times as long as wide, but the ocular lobes are only about halt as long as the velar 

 and about twice as long as wide. Each pair of ocular lobes is, however, mounted upon a 

 common basal projection which causes them to project beyond the contour of the velar lobes. 



There are 24 tentacles and 8 sense-organs 

 arranged so that 2 marginal lappets are placed 

 between a tentacle and a sense-organ or between 

 two successive tentacles. The adradial tentacles 

 are the longest. There are powerful muscle fibers 

 on the axial side and transverse bands of nemato- 

 cysts on the abaxial side of each tentacle. 



The subumbrella is nearly smooth with weakly 

 developed muscles. The canal-system is as in 

 Discomedusa philippina (see page 607) except that 

 the perradial and interradial canals are less com- 

 plex in their branching and there is but a single, 

 blindly ending side branch from the ring-canal in 



each , ; j f ^ p phl l lppma 



I r ' r r r 



D. philippina may, indeed, be only the young of 

 P. polylobata, and later the 32 lappets may divide to form 64. The large size of the gonads 

 and complex branching of the interradial and perradial canals in D. philippina, however, 

 cause me to hesitate before drawing this conclusion. The bluntly rounded lappets of D. 

 philippina are also very different in shape from the long pointed ones of P. polylobata. 

 In any event P. polylobata was evidently derived philogenetically if not ontogenetically 

 from some such medusa as D. philippina. 



The oesophagus of P. polylobata is about as long as the bell-radius, is 4-sided and pris- 

 matic, and the richly folded, lanceolate lips are as long as the mouth-tube. They are thick 

 and keeled along the midrib, and their margins bear numerous minute filaments. The 4 long, 

 narrow gonads are about 5 times as wide as the perradial spaces between them. The medusa 

 is colorless and nearly transparent. It was found in large numbers in a haul of a shrimp-trawl 

 in Toyama Bay, Japan, in June, 1907, from a depth of about 65 fathoms. 



Kishinouye gives excellent figures of the medusa. 



FOSSIL MEDUSA. 

 Ephyropsites jurassicus von Ammon. 

 Ephyropsites jurassicus, VON AMMON, 1908, Geonostischen Jahreshcft, 1906, Jahrg. 19, p. 169, taf. 3, 2 fign. 



This is one of the Coronatce closely allied to Nausithoe. It is from the Upper Jurassic 

 limestone of Pfalzpaint. Bell 150 mm. wide with a distinct annular furrow and a pedal zone 

 40 mm. wide. 8 tentacles and 8 rhopalia. 16 pedalia in the radii of the tentacles and sense- 

 organs. The tentacular pedalia are twice as wide at the zone of the tentacles as the rhopalar 

 pedalia. A median ridge upon each pedalium, and near the margin on the rhopalar pedalia 

 a pair of short, radiating ridges, each ot which gives off a divergent cross-furrow arising from 

 the inner end of each radiating ridge. There are ring muscles in the subumbrella. A single 

 impression of this medusa was studied by von Ammon. 



FIG. vS.-P a run*rosapoIyloba,a After Kishinouye, in 

 Journal College ot ocience University ot iokyo. 



