P. L. KRAMP. 



[REP. 01 r THE "MICHAEL SARS" NORTH 



LEPTOMEDUSAE. 



S. Chromatonema rubrutn Fewkcs. 

 Plate I, figs. 5, 6. 



Chromatonema rubrutn Fewkes 1882, Bull. Mus. Comp. Zool., Harvard 



Coll., vol. 9. No. 8, p. 305, PI. I, fig. 41. 

 Thaumantias Mayer 1910, Medusae of the World, I. p. 199. 



Kramp 1913, Vidensk. Meddel. Dansk naturhist. 

 Foren., Bd. 65, p. 267. 

 1914, Meduser etc.. Conspectus Faunae 

 Groenlandics, p. 419. 

 ? Ptychogena er^'throgonon Bigelow 1909, Mem. Mus. Comp. Zool., 



Harvard Coll, vol. 37, p. 150, PI. 5 fig. 

 1, PI. 38 figs. 8, 9, PI. 39 figs. 1—7. 

 Hertwigi Van'HOFFEN 1911, Deutsche Tiefsee-Exped., p. 

 220. Taf. 22 Fig. 9. Textfig. 13. 



Stat. 70. Lat. 42° 59' N, Long. 51° 15'W (southern 

 edge of the Newfoundland Bank), June 30th 1910. Ring- 

 trawl with 700 m. wire. — 1 specimen. 



Stat. 80. Lat. 47° 34' N, Long. 43° 11' W (eastern 

 slope of the Newfoundland Bank), July 11th 1910, depth 

 ca. 2000 m. 



a. Young-fish trawl, 1000 m. wire. — 2 specimens. 



b. Ringtrawl, 1500 m. wire. — 2 specimens. 



Stat. 81. Lat. 46° 02' N, Long. 39° 55' W, July 

 12th 1910. 

 a Ringtrawl, 100 m. wire. — 1 specimen. 



b. Young-fish trawl, 1000 m. wire. — 1 specimen. 



c. Young-fish trawl, 2000 m. wire. — 1 specimen. 



Stat. 82. Lat. 48° 24' N, Long. 36° 53' W, July 

 13th 1910. 



a. Young-fish trawl, 1000 m. wire. — 1 specimen. 



b. Young-fish trawl, 2000 m. wire. — 1 specimen. 



Stat. 84. Lat. 48° 04' N, Long. 32° 25' W, July 

 15th 1910. 



a. Ringtrawl, 2500 m. wire. — 1 specimen. 



b. Young-fish trawl, 3000 m. wire. — 1 specimen. 



Description of the adult. — The bell is somewhat 

 higher than a hemisphere, the gelatinous substance very 

 thick. The manubrium consists of a quadrangular stomach 

 and a short wide mouth-tube; the mouth is provided 

 with four short lips. The stomach is attached to the 

 subumbrella along the arms of a perradial cross, so that 

 there are four triangular pouches between the dorsal wall 

 of the stomach and the subumbrella. There are four 

 radial canals. The proximal part (V2 — -I -a) of each radial 

 canal is wide and contains the gonads; the distal part is 

 straight and narrow and communicates with the narrow 

 ring-canal. The entrance from the side-wall of the stomach 

 to the radial canal has the shape of a perpendicular slit, 

 somewhat broader at the top than at the bottom. A 

 transverse section of the gonadial part of the radial canal 

 is pear-shaped in the proximal part, nearly circular in 

 the distal part. The line along which the canal is attached 



to the subumbrella sends out a number of short lateral 

 branches, so that the attachment of the dorsal wall of 

 the canal has the shape of a pinnate figure. In each of 

 the radial canals there are two rows of sack-shaped gonads, 

 attached to the dorsal wall of the canal in the spaces 

 between the above-mentioned lateral branches of the line 

 of attachment and hanging down into the cavity of the 

 canal. Each of the gonads has a narrow ectodermal 

 lumen, the opening of which is seen as a small fissure 

 in the dorsal wall of the canal (see figs. 5 and 6). The 

 gonads do not communicate with one another. There 

 are from 10 to 16 gonads on either side of the canal. 

 The side-walls of the canal are as a rule tightened close 

 over the sacks, so that the wall becomes faintly lobed or 

 undulated (see fig. 6 b). Frequently some of the proxi- 

 mal gonads are developed in the dorsal wall of the 

 stomach on both sides of the cross-arms. 



There are about 24 tentacles, all of the same shape 

 and size. The tentacular bulb is conical with a heart- 

 shaped base. Between every two successive tentacles 

 there are two (rarely one) short appendages, cylindrical 

 or somewhat spindle-shaped, provided with a battery of 

 nematocysts in the distal end. These appendages are, I 

 think, homologous with cordyli (see below). — The velum 

 is thin and narrow. 



The colour of the manubrium, the radial canals, 

 the ring-canal, and the tentacles is brightly orange or 

 brick-red. The gonadial sacks are white. 



Dimensions: The diameter of the specimens brought 

 home by the "Michael Sars" varies from 16 to 27 mm. 

 The specimen figured in plate I fig. 5 has the following 

 dimensions: diameter of the bell 26 mm., diameter of 

 the bell cavity 18 mm., height of the bell ca. 20 mm., 

 the sides of the stomach 4.2 mm., distance from the cen- 

 tre of the stomach to the distal ends of the gonads 8 — 9 mm. 



Fewkes' description of this species (1882) was based 

 on 7 specimens, obtained by the U. S. Fish Commission 

 off the coast of New England. His description was rather 

 deficient. I have no doubt, however, but that the speci- 

 mens found by the "Michael Sars" belong to the same 

 species. The species was also found by the "Tjalfe"- 

 Expedition in the Davis Strait (Kramp 1913). — Thus this 

 interesting and beautiful species seems to be common in 

 the intermediate water of the North-West Atlantic basin. 



Bigelow (1909) has described a similiar medusa 

 from the eastern tropical Pacific; he called it Ptychogena 

 erythrogonon. Bigelow possessed a series of specimens 

 in different stages of development, the largest being 38 

 mm. in diameter with about 64 tentacles. The manubrium, 

 the radial canals, the gonads, and the tentacles have the 

 same shape and colour as in Chromatonema rubrum. 

 According to the description Bigelow's species possesses 



