BiGELOW: MEDUSAE AND SIPHONOPHORAE. 375 



nematocyst ribs of Pandea, or of Browne's (1916) Leuckartiara gardi- 

 neri. But cross-sections prove that in reality they are canals, with 

 well-developed entodermal layer, not solid ectodermal thickenings. 

 Presumably their lumens connect with those of the tentacles to which 

 they correspond. To my surprise no nematocysts were to be found 

 in them, either on sections, or on surface examination with the micro- 

 scope. But unfortunately, the histological condition of the specimen 

 was poor, most of the ectoderm being destroyed along these canals, 

 though persisting on the exumbrella flanking it; hence it is best to 

 lay no stress on the absence of nematocysts. Nothing to correspond 

 to these canals has ever been described for any pandeid; but it is 

 possible that the exumbral bands of Leuckartiara gardineri are like- 

 wise canals in reality. And since, so far as I know, the microscopical 

 structure of the exumbral ribs of Pandea has not been studied, they 

 too, may be hollow. Exumbral canals of this type, though certainly 

 unusual, are fundamentally nothing more than extreme prolongations 

 of the tentacular bulbs, which, in most pandeids, clasp the exumbrella 

 more or less. Browne (1916) surmises that the exumbral bands of 

 Leuckartiara gardiyieri are brilliantly colored in life: after preservation, 

 however, they are colorless in our specimen of Eutiara. The canals 

 opposite the radial tentacles extend upward almost to the apex of the 

 bell, the interradials only to about its mid-level, (Plate 1, fig. 1); 

 their unequal lengths suggesting that they, like the two series of tenta- . 

 cles, radial and interradial, are developed successively. 



Manubrium. The manubrium is large, hanging slightly below the 

 mid-level of the bell-cavity, its capacious cavity domed above, as 

 already noted, the mouth wide open, the hp apparently crenulated, 

 but too much torn for accurate description. The so-called "mesen- 

 teries," which are in reality nothing but the expanded bases of the radial 

 canals, are well developed, the lines of union between canal and manu- 

 brium extending over practically the whole length of the latter, from 

 lip to apex, the four slit-like openings of the canals almost completely 

 subdividing the walls of the manubrium along the perradii (Plate 1, 

 fig, 2). The general structure of these " mesenteries " is already well 

 known for Leuckartiara (Hartlaub, 1913); what is interesting here is 

 the high degree to which they are developed. 



Gonads. The sexual folds (Plate 1, fig. 2) are reducible to the Neo- 

 turris type (Maas, 1904b; Bigelow, 1909a; Hartlaub, 1913), there 

 being two series of adradial folds in each quadrant of the gastric wall, 

 which are not confluent at their interradial end as in Leuckartiara, 

 but independent of one another (the distinction between these two 



