206 THE MEDUSAE. 



of sexual products in the interradii, although in these planes they are re- 

 stricted to the basal end of the manubrium. The gonads, as Maas (: 04*=) has 

 pointed out, are horseshoe-shaped structures, their arms lying along the side 

 of the radial canals. I have been unable to determine whether there is any 

 interruption in the perradii ; and it is probable that there is not, but that in 

 P. violacea, as in P. conica (Maas, : 04°) the four primary gonads form a 

 practically continuous ring surrounding the manubrium. The surface of the 

 gonads is smooth, without transverse folds. 



The manubrium is shorter and broader, and the mouth broader than 

 Mayer has figured them (: 00'', pi. 1, fig. 1), but the difference is no greater 

 than can readily be explained as due to different states of contraction or to 

 the preservation of the Acapulco specimens. There is no peduncle. The 

 mouth is surrounded by four simple lips. There is an ocellus at the base of 

 each developed or rudimentary tentacle (PI. 41, fig. 10, o). 



Color. — The ocelli were Vandyke brown in life ; the gonads opaque, 

 slightly pinkish. Mayer observed a green streak running along the outer 

 surface of the endodermal lining of each radial canal, but this was absent 

 in the present specimens. 



The chief difference between Pandea violacea and the well-known P. 

 conica of the Atlantic is that the former entirely lacks the exumbral nemato- 

 cyst ribs which appear to be specifically characteristic of the latter. 



Tiara Lesson, 1837. 

 sens. em. Hartlaub ('92). 



Tiaridae with horseshoe-shaped interradial gonads, their concavities di- 

 rected distally, their arms transversely folded. Tentacles in one series ; radial 

 canals with only small glandular evaginations, if any ; lips complexly folded. 



To the above definition, which is essentially that of Hartlaub. ('92), 

 Maas has added : — " Tentakel in regelmJissiger Weise auf die 4-Zahl zuriick- 

 fuhrbar" (: 05, p. 14). This statement, is no doubt true in general; but 

 inasmuch as I have found a variation from it in two of the four specimens 

 of the genus in the present collection, I hesitate to adopt it as one of the 

 distinctive characteristics of the genus. The present series agrees well with 

 Maas's account of the " Siboga " specimens, which he refers to T. papua 

 Lesson. This identification cannot be made positive, on account of the un- 

 satisfactory nature of the older illustrations of T. papua ; but so far as one 



