TRAC'HYMKDUS.E — PANTACHOGON. 



389 



Pantachogon haeckelii Maas. 



Pantachogon haeckelii, Maas, 1893, Ergeb. der Plankton Expedition, Bd. 2, K.c, p. 17, taf. I, fig. 2; 1904, Result. Camp. Sci. 

 Prince de Monaco, fasc. 28, p. 29. 



Bell half-egg-shaped with thin walls and without apical projection; 8 to 12 mm. high, 



6 to io mm. wide. Velum large, 2.5 to 3 mm. wide. About 64 well-developed tentacles. 



Numerous nettling warts upon bell-margin. Lithocysts ( ?) Stomach with an 8-sided base and 



4 lips. 8 narrow, straight radial-canals. The 8 gonads are developed as irregularly placed, 



narrow, spindle-shaped bodies on both sides of the radial-canals, from stomach to bell-margin. 



One specimen found by the Plankton expedition at a depth of 300 fathoms, in N. lat. 6o°, 



southwest of Iceland, in July, 1889. Another found by the Prince of Monaco at Spitzbergen, 



in 1899. 



240. 



Fig. 239. — Pantachogon haeckelii, after Maas, in Ergeb. Plankton 



Exped. 

 Fig. 240. — Pantachogon rubrum, after Maas, in Hydromedusen, Siboga 



Expedition. 



Unfortunately, the color is unknown and it is possible that this Arctic species may prove to 

 be identical with the deep-water P. rubrum of the tropical Atlantic and Pacific. P. haeckelii 

 appears to become mature when smaller than P. rubrum, but much allowance for variation 

 must be made when comparing preserved specimens one with another, especially where the 

 examples are few, as in this case. 



Pantachogon rubrum Vanhbffen. 



Pantachogon rubrum, Vanhoffen, 1902, Wissen. Ergeb. 

 deutsch. Tiefsee Expedition, Dampfer V aldivia, Bd. 

 3, Lfg. 1, p. 63, taf. 9, fig. 9; taf. 10, fign. 19, 20; taf. 

 11, fig. 25. — Maas, 1905, Craspedoten Medusen der 

 Siboga Expedition, Monog. 10, p. 55, taf. 10, fig. 66. 



(!) Pantachogen haeckelii, Maas, 1893, Ergeb. der Plankton 

 Exped., Bd. 2, K. c, p. 17, taf. 1, fig. 2. 



According to VanhofFen the bell is 13 

 mm. high, 10 mm. wide; according to Maas, 

 6 to 12 mm. high and 9 to 15 mm. wide. 

 These discrepancies are doubtless due to 

 degrees of contraction in the preserved speci- 

 mens. Bell dome-shaped with thin walls 

 and evenly-rounded apex. 



Fin. 241. — Pantachogon rubrum, after VanhofFen, in Tiefsee 

 Expedition Valdivia. 



There are 64 tentacles which are quite similar each to each and lack swollen, basal bulbs, 

 such as are seen in Homceonema (Colobonema) typicum, but are of uniform width throughout. 

 The complete tentacles have never been seen, however, for they were broken off quite close 



