HYDROMEDUSAE, SIPHONOPHORES, AND CTENOPHORES. 285 

 NEOTURRIS PILEATA (Forskil) Hartlaub. 



Plate 39, figs. 7, 8 ; plate 40, fig. 1. 



Medusa pileata Forskal 1775, p. 110. 



Neoturris pileata Hartlaub, 1913, p. 326. To the synonymy given by Hart- 

 laub, 1913, p. 326, add Turns pelagica; Agassiz and Mater, 1902, p. 142, 

 pi. 1, fig. 2.— Mayer, 1910, p. 127. 



Both the examples are in go.od condition, though somewhat con- 

 tracted. But in each a small portion of the margin is so damaged 

 that it is impossible to determine the total number of tentacles within 

 two or three. The specimens are described here in detail, as no ac- 

 count of adult Pacific examples has appeared. 



The tentacles seem at first sight to be arranged in two alternating 

 rows, an inner and an outer. But this appearance is merely superficial, 

 for all the tentacles arise at the same level, close to the circular canal, 

 and the apparent outer row is merely the older tentacles, whose bases 

 are broader and reach outward farther than those of the younger ones. 

 A side view of the margin (pi. 39, fig. 8) shows the actual relation of 

 the tentacles of different ages more clearly than a verbal description. 

 The tentacle bases are laterally flattened and triangular. There are 

 openings on the outer face of several of the bulbs near the base, but 

 these are apparently accidental mutilations, not true ostia such as 

 occur in N. fontata. 



In the smaller specimen there are six rudimentary knobs, but there 

 are none in the larger. Evidently, then, the number of tentacles pres- 

 ent is nearly, if not quite, the final one. There are no ocelli ; nor are 

 ectodermal sensory pits, so important a feature of N. fontata, present. 

 But there is a shallow furrow in the exumbrella just above the base 

 of each of the larger tentacles. I was not able to study the histology 

 of the ectoderm in this region because of the condition of the 

 specimens. 



Manubrium and gonads. — The manubrium occupies but little more 

 than one-half the depth of the bell cavity; the lips are thrown into 

 numerous small complex folds (pi. 39, fig. 7). 



The gonads (pi. 39, fig. 7), which closely resemble the figures of 

 N. pileata given by Maas (1905, pi. 1, fig. 5) and Hartlaub (1913), 

 are entirely discontinuous in the perradii, but connected in the upper 

 half of the interradii by an irregular network. 



