384 



MEDUSA OF THE WORLD. 



Big-elow, who studied a large number of specimens, decides that Homceonema typtcum of 

 Maas 1897, is specifically distinct from "Colobonema sericeum" of Vanhoffen, 1902; but Maas, 

 who has seen both forms, states that they are identical. I have placed " Colobonema sen- 

 ceum" provisionally in the genus Homceonema, and incline, although doubtfully, to follow 

 Maas in considering it as being synonymous with Homceonema typicum. Future studies 

 may demonstrate that Colobonema should be separated generally for Homceonema, as has 

 already been done by Bigelow, 1909. . 



In 1906, Maas institutes a genus Isonema with tentacles similar each to each and in a 

 single row, and with gonads adjacent to the sides of the stomach. Maas proposes this genus 

 for Homceonema am plum, Vanhoffen, 1902. I can not separate it from Homceonema. 



Synoptic Table of the Species of Homceonema. 



Shape and size of 

 bell in mm. 



Number and char- 

 acter of tentacles 



Homoeonema typi- 

 cum Maas, 1897 = 

 Colobonema seri- 

 ceum Vanhoffen, 

 1 902= Colobonema 

 tvpicum Maas, 

 1905. 



Dome-like, higher 

 than a hemisphere. 

 45 wide, 35 high. 



32. All of same size. 

 Flattened tangen- 

 tially. 8 oldest, 

 radial 4- 16 next 

 oldest, adradial + 

 8 youngest, inter- 

 radial. 



Homoeonema ara- 

 plum Vanhoffen, 

 1 902= Isonema 

 amplum Maas, 

 1906. 



Number and char- ? Not seen, 

 acterof lithocysts. 



Length of manu- 

 brium in terms of 

 depth of bell- 

 cavity. 



Shape and position 

 of gonads. 



Flatter than a hemi- 

 sphere, evenly 

 rounded. 15 wide. 



"18 + , all of similar 

 size and character. 



4 or none. 



Homoeonema macro- 

 gaster Vanhoffen, 

 1902. 



Homoeonema mili- 

 tare Maas, 1893. 



Homoeonema platy- 

 gonon Maas, 1893; 

 Browne, 1903. 



Color. 



Where found. 



Distinctive 

 characters. 



One-third to 1. 

 Very variable in 

 length. 



Spindle-shaped. On 

 about 0.75 of 

 length of radial- 

 canals, leaving both 

 ends free. Gonads 

 begin to develop on 

 outer parts of ra- 

 dial-canals. 



Colorless, very iri- 

 descent, or irides- 

 cent light-brown ? 



From depths of 115 

 to 1,500 fathoms. 

 Tropical Atlantic 

 and Pacific. 



32 tentacles, having 

 very characteristic 

 mode of develop- 

 ment. Gonads on 

 three-fourths 

 length of radial- 

 canals. 



Very small. —0.2. 



8 spherical gonads 

 upon radial-canals 

 adjacent to stom- 

 ach. 4 gonads are 

 large, alternating 

 with 4 small 

 gonads. 



Colorless. 



Bouvets Islands, 

 South Atlantic near 

 Antarctic circle. 



1 spherical gonads, 4 

 small alternating 

 with 4 large. All 

 close to sides of 

 stomach. 4 litho- 

 cysts. 



Evenly rounded. 7 

 wide. 



84, all of same size 

 and character. 



32. 4 in each octant. 

 Definitely spaced 

 between tentacles. 



Large. Exact size? o-5± 



Miter-shaped with 

 well-developed 

 projection 7 to 10 

 wide. 6 high. 



5o±. All about 

 equally developed. 



4 club-shaped. 



Hemispherical, to 

 higher, with a low, 

 hollow, dome-like 

 apex. 2 to 4 wide. 



40 to 80, all similar. 



8 spherical on 8 ra- 

 dial-canals adja- 

 cent to sides of 

 stomach. Gonads 

 all of same size. 



Bell-margin dark- 

 colored, other parts 

 colorless. 



Southern part of 

 Indian Ocean from 

 depth of 100 

 fathoms, S.lat. 

 3o°7', E.long. 



87° 5°'- 

 8 spherical gonads as 

 in H. amplum, but 

 all of similar size. 

 32 lithocysts. 



8 wide lancet-shaped 

 on outer halves of 8 

 wide radial-canals 

 above ring-canal. 



Tropical Atlantic, 

 Bermudas, Medi- 

 terranean. 



4 vesicular, in middle 

 of alternate inter- 

 radii. 



0.25 



8 wide, flat, sur- 

 rounding base of 

 stomach and ex- 

 tending one-third 

 to half-way out 

 along 8 radial- 

 canals. 



Stomach, gonads, 

 and canals opaque 

 Other parts trans- 

 parent glassy. 



North Atlantic, 

 coast of Norway. 



5o± tentacles all 

 quite similar each 

 to each. Very wide 

 radial-canals. 

 Club-like, lithocyst 

 organs. Gonads 

 on outer half of 

 radial-canals. 



5o± tentacles all 

 quite similar each 

 to each. Radial- 

 canals not very 

 wide (Browne). 

 Lithocysts vesicu- 

 lar. Gonads adja 

 cent to sides of 

 stomach. 



