MKOUS^. 17 



dcfinitiou, aud instead of sayiiif; " minierou.s " ccntripotal canals, to fix tlie nunilicr at 

 four or more. 



The type species of the ifcnus SUmgita is S. i/eovietrica, Maas. This Medusa, 

 according to Maas' figure, certainly has the appearance of possessing radial canals with 

 lateral branches, as stated by Maas, aud there is no indication of the lateral branches 

 being really centripetal canals, which originate from the circular canal and afterwards 

 join the radial canals. 



It was my intention to place the Antarctic species in a new genus, but Mr. 

 Bigelow's account of the development of the canal .system of Sihot/ita siniulans has leil 

 me to place the new species in the genus Siboc/ita. I believe that ^[r. Bigelow is rio-ht 

 in associating his two new species with the genus Slhoijila, especially as the tentacles 

 and the umbrella are similar to those of the type .species. 



The two specimens of Sibogita simulans collected in the tropical Pacific have eight 

 adradial blind centripetal canals, but tlie single specimen from the Behring Sea is older 

 than those two and has twelve centripetal canals, which all unite with the base of the 

 stomach. In S. nauarchus the centripetal canals are more immerous and are all lilind. 

 Sibogita burchgreviiiki has only four centripetal canals, which may or may not unite by 

 lateral branches with the base of the stomacli. 



In the species described by Dr. Maas and by Mr. Bigelow the gonads are 

 transversely folded, and occupy the whole space between the perradii. The gonads of 

 the new Antarctic species are distinctly peculiar, as they are in pockets, and the whole 

 stomach is converted into a reproductive organ. 



Sibogita borchgrevinki. 

 (Plate II., fig.s. 1-5.) 



Description of the Species. — Umbrella ovoid, a little higher than broad, and very 

 thick. Velum narrow. Stomach about one-third the lengtli of the unibrellar cavity, 

 somewhat conicid, tapering .slightly t(jwards the mouth, and with four perradiul ridges. 

 Mouth with four small lips and the margin slightly folded. Four perradial canals, 

 and four interradial centripetal canals. The latter may or may not unite with 

 the cruciform base of the stomach. Gonads (male) in pockets and embedded in 

 the wall of the stomach, with definite openings to the exterior. About sixteen 

 fairly long, hollow, smooth tentacles, each witji a large terminal bulb containing 

 nematocysts. 



Size. — Umbrella 15-18 mm. in width and 20 mm. in height. 



Three specimens of this interesting Medu.sa were taken at the .surface during 

 November 1899 at Cape Adare by the 'Southern Cro.ss' Expedition. The .specimens 

 are in very good conMition, but all have the margin of the umbrella so very much 

 contracted that it was necessary for examination to cut it into pieces. Two of the 

 specimens are fully ripe males, and the third .specimen has shed its gnnad.s. 



