BIGELOW: MEDUSAE AND SIPHONOPHORAE. 373 



is an Aglantha, and one a Sarsia; partly from the limitation of the 

 genus to pandeids in which the gonads form a net-work, which ex- 

 cludes P. violacea Mayer. I too, formerly classed the latter as a 

 Pandea (1909a) in describing specimens from the west coast of Mexico, 

 defining Pandea as "Tiaridae with horseshoe-shaped gonads" (1909a, 

 p. 205). But as Hartlaub (1913) and Vanhoffen (1911) have pointed 

 out, the gonads of the type-species, conica, form a net-work; a type of 

 sexual de\-elopment shared by the mesoplanktonic Pandea rubra 

 recently described (Bigelow, 1913, p. 14). And inasmuch as the 

 structure of the gonad has proved to be a very useful taxonomic 

 character, in fact the only trustworthy one, among the polytentacular 

 pandeids, it is wisest to follow Hartlaub in his limitation of the genus, 

 referring the Pandea violacea of INIayer (1910) and Bigelow (1909a) 

 in which the gonads are smooth, to the new genus Merga, established 

 by Hartlaub (1913, p. 249) expressly for it. To Merga likewise belongs 

 the Pandea sp. of Lo Bianco (1903), for though Hartlaub (1913, p. 

 250) thought it deserved a separate genus, Mergintha, the only char- 

 acter separating it from Merga, its folded lip, is not of more than 

 specific value. This leaves P. conica Quoy and Gaimard, and P. rubra, 

 Bigelow as the sole representatives of Pandea. Pandea rubra is 

 separable from P. conica bj^ its large size, deep red pigmentation, 

 extremely complex gonad-net, and by the absence of the exumbral 

 nettle ribs so characteristic of P. conica. 



Pandea conica (Quoy and Gaimard). 



Dianea conica Quoy & Gaimard, 1827, p. 182, pi. 6A; fig. 3, 4. (For synonymy, 

 see Mayer, 1910, p. 118; Hartlaub, 1913, p-. 338). 



Station 10,171, 75-0 meters, 1 contracted specimen, 9 mm. high by 

 9 mm. broad. 



This specimen is undoubtedly a Pandea; and in its main features 

 resembles P. conica so far as can be seen in its present imperfect and 

 distorted state. But it is with some hesitation that I refer it to that 

 species, because of the minor differences enumerated below. A larger 

 series might show that it represents a new, though allied, species. 



In its general form; in the net-like structure of its gonads; in the 

 presence of well-developed "mesenteries" involving all but the oral 

 end of the gastric wall; in the smooth walled radial canals; the occur- 

 rence of exumbral nettle-ribs, one to each tentacle; the structure of the 

 tentacular bulbs; the presence of abaxial pcelli; and in pigmentation, 



