556 



MEDUSAE OF THE WORLD. 



is at the extremity of a short, blunt-conical hypostome, which is surrounded by an annulus 

 of about 40 solid filiform tentacles. 4 longitudinal partitions lined by entoderm extend 

 throughout the cavity of the stem. These do not meet in the center, but form only partial 

 septa, comparable with the mesenterial partitions of other scyphostomae of Scyphomedusze. 

 There is no marginal ring-canal. There are external, longitudinal and internal (meso- 

 dermal) circular muscles. The polypites are translucent-white. 



Lobianco and Paul Mayer, 1890, found that ephyrae of Nausithoe arise by strobilization 

 from this larva. The young ephyra has only 4 gastric filaments and no tentacles. Kowal- 

 evski, 1873, also observed the giving off of the ephyrae, but did not determine that they were 

 Nausithoe. 



It is not surprising that this peculiar larva should have received various names: Allman 

 calls it Stephanoscyphus mirabilis; F. E. Schulze describes it in detail under the name Spotig- 

 icola fstularis; but its true nature was discovered by Lobianco and Paul Mayer, 1890. 



Haeckel's Nausicaa phtsacum from Corfu, Mediterranean, may be identical with N. 

 punctata, but the 8 gonads tend to be grouped in 4 interradial pairs, forming a broken crescent 

 in each interradius, with a wide separation between the outwardly directed horns of each 



crescent. It may have been described 

 from an abnormal or young specimen 

 of N. punctata (See Haeckel, 1880, Sit- 

 zungsber. Jena. Gesell. fur Med. und 

 Natur., Jahrg. 1880, Feb. 20.) 



Nausithoe clausi Vanhoffen. 



Nausithoe clausi, VANHOFFEN, 1892, Ergeb. der Plank- 

 ton Expedition, Bd. 2, K. d., p. 14, taf. 4, fign. 

 I, 2. 



Disk about 9 mm. wide; central 

 lens-shaped dome of exumbrella flat, 

 smooth, unpitted, and without radial fur- 

 rows; 5 mm. wide, 16 well-developed 

 marginal pedalia. Medusa 3 times as 

 wide as high. 1 6 very blunt, 3-cornered 

 marginal lappets, three times as wide as 

 long and hardly one-ninth as long as 

 bell-radius. 8 adradial tentacles with 

 well-developed, conical bases. Tentacles 

 as long as bell-radius. 8 marginal sense- 

 organs alternating with tentacles. 8 gonads in the tentacular radii, very small, spherical, 

 only 1.3 as wide as the pedalia. Ring-muscle of subumbrella one-third as wide as bell- 

 radius. Numerous, small, simple gastric cirri arising in a linear row in each interradius. 

 Color (?) 



Pacific Ocean east of the Caroline Islands. A single specimen appears to be AT. punctata 

 with poorly developed marginal-lappets and small gonads. 



Nausithoe challenged Vanhoffen. 



Nauphanta challenger!, HAECKEL, 1880, Syst. der Medusen, p. 487; 1881, Report Deep-sea Medus.T, Challenger Exped., Zool., 



vol. 4, p. 103, plates 27, 28, 20 figs. 

 Nausithoe challenger!, VANHOFFEN, 1902, Wissen. Ergeb. deutsch. Tiefsee Exped. Valdivia, Bd. 3, Lfg. I, pp. 28, 31. 



Bell 12 mm. wide. Central lens of exumbrella separated by a deep annular furrow from 

 zone of pedalia. Somewhat less in diameter than bell-radius, its margin cleft by 16 radiating 

 furrows which do not extend to center of exumbrella. Marginal zone of pedalia well developed, 

 the 8 ocular being narrower than the 8 tentacular. Tapering tentacles somewhat longer than 

 bell-radius. The 8 large gonads are twice as long as wide and are elongated outwardly. 

 They are somewhat wider than the intervals between them. 4 interradial clusters of simple 

 gastric cirri which arise at equal spaces in a single row in each cluster and are not grouped 

 into brushes as in N. albatrossi. Each cluster has about 24 cirri. 



FIG. 355. Nausilhoe rubra, after Vanhoffen, in I'aldtvia Expedition. 



